I'll copy my answer from your other thread (and add a bit to the end of it):
The symptoms that you've described could be related to many, many things. As an experience first aider (who used to deal with the aches and pains of hundreds of kids in the school that I taught at, even though they weren't really 'first aid' problems), the first question that I'd be asking you if you presented yourself to me with those symptoms would be "Have you banged your head within the past day or two?", as (among many other things) they're symptoms of concussion. [I once picked up on a lad who'd fractured his skull a day earlier, when falling off his bike].
My next consideration might be the possibility of ingestion of any type of chemicals or drugs (whether deliberate or accidental and whether legal or otherwise). Alcohol can explain such symptoms, as well as certain types of chemical fumes and, of course, illegal drugs.
After that, a vast number of different viruses or, for example, bacteria leading to food poisoning, could come into play in trying to find the cause of your problems.
Additional bit:
If you've banged your head within the past couple of days, get to A&E as soon as possible. Otherwise, if you're starting to feel a bit better, just monitor the situation while keeping your fluid levels up. If you feel really bad, with no obvious cause, and you're starting to worry, call 111 for advice.