Hello
You didn't mention about the sexual relation history in recent past , this is very important .
If you have sex within one year with an unknown person then please get in blood for H IV ( because
diarrhea, nausea or vomiting, general weakness, burning sensation , generalized
body ache are all an indication of HIV infection , if contact history is there).
The next reason of such symptoms may be due to
peripheral neuropathy ( reason may be
diabetes or deficiency of B12 ) . So for this consult a physician and get his opinion.
As you mentioned that there is discharge from penis , so this discharge in young ( 17 -18 years ) may be due to semen ,
phosphaturia or pus .
Get in swab examination for this discharge .
As your history of illness is very ambiguous so very difficult to estimate the diagnosis .
In my opinion consult a physician and get his opinion as physical as well as clinical examination is very important in such type of cases.
Good luck.