im 15 and really scared :(

Abour a week and a half ago my boyrfiend and i were like fooling around and at one point he did put it in, but it was literally there for a SECOND, and since we didnt have a condom we both agreed that it'd be dumb if we had sex. Then like a day or two later i had like cramps at the bottom of my stoamchq nd digestional issues, and a lot of watery mucus, then it turned into a more boogery mucus and now its just creamy white discharge. My period is due june 5th or something like that but right now im constipated, for the paat theee days i havent been able to gone to the bathroom without feeling like i pooped everything out. I do feel tired but i mean i think its cause i fo to sleep late. I also have this odd headache idk how to explain it. BTW he never came theoughout the whole time. Im just so scared please tell me that im just having PMS :(