pregnant? or is it just sympotoms from my medicine?

My boyfriend and i almost had sex, but i stopped him before he went in. he touched my vagina but i think there was precum on his thingy and or it could have been me because we were doing other stuff before.he wasnt wearing protection. im scared that "swimmers" went through my vagina. im on birth control for heavy periods (4 months) and i forgot to take my pill the night before, but i took as soon as i remembered the next morning (that night was when this incident happened.) therefore i took 2 that day. and since its spring, i have really bad allergies. my doctor prescribed me amoxicillin, which makes the birth control less effective. its been 5 days since this happened and my stomach is bloated and i keep tasting this metallic taste in my mouth. i am peeing several times but only a little bit. and im having some discharge. im scared that i am pregnant. and or it could just be the amoxicillin. could you please give me some input asap, thanks so much.