Food aversions, lost of appetite,tired...whats wrong with me ?

Ive been having unprotected sex (withdrawal) since early this year,but I took Plan b 2 times and I have also been getting my period every single month.I feel tired and all I want to do is lay down and do nothing at all.I have no appetite and dont seem to enjoy food like before.I drank on friday and saturday and thought it was just a hangover,but after 3 days,I still dont feel like myself.Any idea what could be going on ?