What do you think?????

Okay so for the past three days I've been experiencing minor cramps later in the day and after I eat I'll have cramps, get really bloated, and gas. My period is predicted in 8 days but I usually don't have these problems? I did have sex last Saturday, but my boyfriend swears on everything he was completely clean. So I don't think this would have to do with pregnancy but it has me worried. Could it just be because I was sexually active for the first time in about 3 months? Any thoughts?