Severe cramping but missing period

So my period is 4 days late as of today. I had unprotected sex 3/23 (he didnt finish), and 3/26 (he pulled out before coming, and please I don’t need a lecture about how unreliable the pull out method is). AF was suppose to start 4/10. But clearly hasn’t. I’ve been cramping since 4/10 but nothing yet. I had some severe cramping this morning mixed with diarrhea (sorry tmi). My cycles can range from 26-34 days but usually stays between 29-31. I’m not sure what is going, wondering if I should buy a test or try to wait it out. I keep thinking my period is coming based on the cramps but idk. Oh and I’ve been slight nauseous. Help please!