Pregnant by my boyfriend and I dry humping?

I know that it's possible to get pregnant by dry humping. However, in this situation I was on my hands and knees and he was behind me. I had on a pair of mesh shorts, and underwear. I was also on my period at the time, and had a tampon in. He was in dress pants since he had gotten done with a concert earlier and hadn't changed, he also had boxers on. I didn't think just dry humping would make him cum so I wasn't concerned with that or anything, but it did. And it made his pants pretty wet, I think I remember seeing it like glisten in the light kind of, off of his pants. I felt my shorts but it they didn't feel wet, and they were pink, and I couldn't see anything on them. But he came while I think we were still touching (over clothes you know). So do you think I could be pregnant? This happened May 27th, and randomly today I've had a really bad stomachache and have felt sort of nauseous. But I can't tell if that's just because of something I ate or indigestion or what. Because it did start right after I used the bathroom this morning, and it felt like I needed to get a little more out if you know what I mean. I've used the bathroom since though, and I only feel a little better. I haven't had any other symptoms like soreness in my boobs, or frequent urination. Even though I know it'd still be early. I'm just scared haha. Thanks. I'm definitely not going to let something like this happen again.