My boyfriend had ejaculated in his pants before hand, we are both 99% sure that he changed them for new ones, but either way most of the ejaculation didnt end up in his pants anyway.. But still.. About 20 mins later, we were fooling around and ended up dry humping, i was wearing my under pants ans my boyfriend was wearing his underpants and a pair of gym-style short, (NOT very thin material) and so we dry thrusted (not properly) for about 20 seconds and then we stopped, he did not ejaculate, my underwear was slightly damp due to myself (i think) and neither of us noticed a wet spot on his shorts or anything.. I normally have irregular periods as it is.. And so i am worrying before i need to if i am honest.. About 4 days after it happened i excperienced pains in my riight lower side, and some small stomach ache (but when i am worried/anxious i get stomach ache...) i am worrying. I understand that what we did was stupid and we have both agreed to stay clear for that sort of activity from now on as it has caused worry to the both of us.. Is there any chance of pregnancy? I am very worried.. As i said.. We are pretty sure he changed his boxers.. But even if he didnt would it still be possible? (Please give answers for both examples)