What is this??! ( Please help)

So over the course of the past two years, when my social anxiety levels have been high, I've been experiencing episodes, lasting anywhere from 3 days to over 2 weeks, of something I haven't been able to define or manage very well, and was wondering if anyone here could help me out, particularly because I have to sit my terminal exams soon, and am terrified it will impact upon my academic performance. ( I would also like to add that I've had medium to high anxiety levels over the last three years, accompanied by a constant state of depression, and experienced several panic/anxiety attacks around January to March- although those I can now manage.) My mind somehow convinces itself that I am someone else e.g. someone I've talked to recently, and then I begin to think how my mind perceived they think, if that makes sense...the observations I make, and the opinions and judgements I formulate become tailored to the way my mind perceives their characteristics, often emphasizing aspects I find irritating, which results in a lot of negative thoughts. Essentially it is a very elaborate delusion, however, simultaneously, I AM aware that it is completely irrational while it is happening, but it feels like my mind takes no notice of that and trying to convince my mind that it is absolutely irrational doesn't seem to work, because I get so worked up when it starts to manifest. When I'm not affected by this, I DO have my own viewpoint, and observations, opinions and judgements, but on the other hand, I do internalize a lot of things.
I don't know whether it stems from a chemical imbalance, or anything of that nature, or whether, in trying to embody somebody else's identity, I am subconsciously trying to compensate for the loss of my own. It is probably worth mentioning that, a few months into my depression and at the height of my anxiety, I decided to emotionally 'numb' myself, and it has stayed that way ever since: I feel hollow on the surface, and fake my emotions....the persona I've created for others is artificial, and I don't know where these delusions are a kind of side effect of that? I do relate to some symptoms of depersonalization.
I haven't felt any kind of happiness in a long time (partly my fault, because for a while I was so comfortable within my depression) that it's almost as if my mind has ruled out the prospect as a possibility, it's as if the delusions have to emerge once there's been a slight reduction in workload/ things to worry me,to refill my plate of anxiety, instead of an attempt at recovery. In training myself not to feel, I have, in one respect, conditioned my mind for this kind of response.
If anybody here has dealt with/ is dealing with something similar, PLEASE leave a response...how do I manage or completely eliminate this?

- Sorry that this post was jumbled in that it references a lot of the elements of my situation which may or may not tie, it was just that these 'delusions' have been puzzling me for several months, so I felt I had to get my thoughts down.