Undiagnosed :: Brain Fog With Head Pressure - Feeling Detached

I am male and 26 years old. I have been suffering with the symptoms in the title pretty consistently for about 2 and a half years now. I used to have some relief from the symptoms for a day or 2 here and there or maybe a bit of relief for a few hours in the day but recently the symptoms are pretty much constant and I cannot shake them. 

I have an overall mild pressure feeling in the head, its not painful but is just very aggravating and feels really strange. I also have extreme brain fog with this and like a fuzzy head, there is a constant cloud over my brain and I never have any mental clarity or a clear head. My cognitive function is extremely poor now, my short term memory is non existent, its scarily bad. I often feel, detached from reality when the symptoms are bad and suffer from de-realisation, although I think this may be down to some anxiety and depression I experience when the symptoms run me down. I also get random sharp cramping pains in the head, they are quite painful but do not bother me so much as they only usually last a second or 2, it varies on how many I get of these each day but its usually less than 5. It often feels as though my brain is malfunctioning somehow and my cognitive function and senses are all out of whack, its hard to explain. There can sometimes be a build up of these symptoms throughout the day and by the night I can feel like I somehow how the flu without a fever? Like I have the head pressure, completely foggy headed, I feel super unwell, weak, sometimes even start feeling cold. Also have night sweats usually for about 4 or 5 days each month, there doesn't seem to be any sort of pattern to them that I can notice, so not sure if they are relevant. Another thing I have is ringing in ears which is mild but seems to have gotten worse recently if that sounds relevant at all. The main thing that gets me is the odd head pressure/sensation and the utterly life hindering brain fog, my brain feels like it is coated in a dark blanket constantly.

I do suffer from anxiety, I know many of these symptoms can be caused or made worse by these symptoms. I dont doubt that anxiety is a contributing factor and the way I think about they symptoms probably makes them worse but I have come a long long way with my anxiety, I have good control over it, I haven't had a panic attack in a couple of years, I manage to control most of my concious anxiety and stay in a positive mindset. No doubt I still have some subconscious anxiety underlying and I am working on that but I am not convinced this is the route cause of my symptoms. I am in therapy for my anxiety. I do not feel I will ever fully recover while I have these symptoms hanging over me though. 

I have been to the doctor about these symptoms, although I do think I struggle to explain them or put them across very well in the doctors office. I have have blood tests which are all normal. I saw a neurologist couple of years back when this started, had a CT scan which was normal, they put the stabbing pains down to icepick headaches and thought the other symptoms were probably made worse by my anx/depression. Since then I went away and have been on anti depressants etc with no improvement of symptoms. I have also had a few ECGs and a 24hr ECG as I have slow heart rate and low bp so thought maybe the symptoms could be down to low bp and lack of blood to the brain, doctors do not think think this is the case and all my results came back normal. I have recently been back to the neurologist who is referring me for an MRI although he said he is sure there is nothing sinister and thinks the symptoms are probably tension type headaches and made worse by and previous drug use, he only put it down to the drug use when i told him about it though so it seemed like a convenient diagnosis. I forgot to mention I used to take drugs on the weekends socially, cocaine, ketamine and ecstasy on different occasions for a couple of years, I have had periods where I have felt ok since taking these drugs and do not really think they are the cause, I was not an addict this was just one or 2 nights a month at the weekends. So I have an MRI coming up but the neuro thinks it will be clear and obviously I hope it is and I am looking for other answers. 

What could be causing these symptoms? Other than anxiety which i no can be a factor, but I have periods where my anxiety is pretty much non existent but these symptoms still build up out of nowhere and persist. I was thinking maybe some sort of allergy could be a possibility, I have tried cutting out gluten and lactose, this didn't seem to make much difference although I didn't stick to this for very long. I actually did a juice fast for 2 weeks with eating nothing other than fruit and veg juice put through a juicer to see if that would help but it didn't really give me any relief. Are there any other stomach issues that could cause this? I never have diarrhoea or constipation, my stools always float recently though, to the point of not being able to flush them, also whenever I have seen chance medicine doctors they check me out and say they think i have issues with digestion, i don't feel i have these issues but do wonder if there might be something in it. 

Could there be something going on with the blood vessels in my head? Could it be a spine/posture issue? Some sort of epilepsy or electrical activity in my brain? I just have no idea now and am desperate for some relief. If anyone has any ideas or advice I would really appreciate it. 

Oh just to add I am reasonably fit, I try go to the gym a few times a week and I do some weight lifting. I am a normal weight. I have been losing some weight recently which is a concern but I am still in a normal weight range for height and age.