Help!

I had my period this month and my next one is in 11 days but I'm heavily spotting I did have sex last week! I've been having cramps on my lower stomach and ribs all week! Can anyone please help or tell me why I'm spotting? My period cycle keeps changing we used a condom and he didn't cum in me but idk the signs of pregnancy or if they show this early I'm 18/ so I'm hoping I'm not I can't get to a test either! If anyone else experiences this please lmk! It's heavy spotting!