What is wrong with me, am I sick?

I recently finished my final exams, which i spend about a week and a half prepping for quite intensely. I feel that i performed pretty well on them and i dont feel i could really have done anything else but i feel awful!
During my study time i was feeling really good, very energetic and engaged and satisfied but since the first exam finished i have felt completely dead.
This week i feel like my brain is full of fog, i feel sad, i keep eating tonnes of crap food, i dont want to exercise and i feel generally weak and ill. I dont feel like i can access my emotions at all, like everything is wrapped in cotton wool, i feel like i would like to cry but i can't, i just feel blank.

Iv also lost interest in my crush within the last two days, now i just feel ehh about the whole thing even though i am supposed to meet him and some friends at the end of the week and this would have been great a week ago. Now i dont think i can face the situation and the thoughts of a relationship turn my stomach.

I am 23 but i feel like i am way to young to deal with anything tight now, like i just want to stay at home with my parents.

What is happening here? I know this isn't the normal question for this site but i am worried! I thought it might last for a day or two post exams, because i usually have a bit of a post exam low, but its been over a week now.

What should i do?
What is wrong with me, am I sick?
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