Can someone please help? Has anyone gone through something similar?

I took a plan b pill a day later after my bf came inside me about 2 weeks ago and I’ve been having constant cramps and nausea! I feel a little better now after I ate but not to contradict myself the symptoms are on and off now that I think about it. I took the pill during my fertile window but didn’t ovulate until 3 days after (according to this app and other another app) but idk if it’s accurate but I hope it is. My period is suppose in 4 days. Do you think it’s to early for pregnancy signs or is it from the plan b? I’ve been feeling like crap for 2 weeks now!

Has anyone been through this before?