Ugh, am I sick?

Sooo I have nausea, and really bad back pain, headaches are terrible and I'm cramping. I just got off my period haven't even gotten on my fertility days man, but uh I had sex the day my period came and the period was irregular asf, it came early and left late, so is there a chance of being pregnant or just allergies or something? And I had sex a day or two ago and he came in me I believe, soooo yea