Any ideas? Help

Hello! I need your advice because i dont feel 'right'. I've had unprotected sex on the 2nd&3rd of August but i got my period on the 15th of August. I know most people would say you've had your period you're not pregnant but i don't feel well. I'm having some of the symptoms and i don't know if i'm going crazy? Is it possible that i am? Should i take a test? Thank you ;)