Young and learning (17) please read !!🙏🏼I’m sorry if this is long

Hey ✌🏼, so I’m 17 years old , and in a relationship, also I’m not a virgin. My bf is a marine and when he came over for the holidays me and him had intercourses days before ovulation (WITH A CONDOM!!!-OBVIOUSLY) I didn’t really start to get symptoms until this month,and I’ve been paranoid with the thought that I might be pregnant which I don’t want . Yesterday morning I woke up to a period stain and when I looked at my underwear it was red and pink , so I checked my pjs only because when I do get my period it stains the pants always and yes it did . After me my aunts and nephew went out to eat , and I started getting cramps like HELLLLLLL but there’s no difference because every time I have cramps there always like that then I need to go to the bathroom to do diarrhea, and from there my cramps would not go away then couple mins into me suffering basically I throw up the food I had ate but I obviously I drank two pills to relieve and honestly throwing up did relieve the pain , then I get home and after I’m done getting ready for bed I notice that when I get up I don’t feel the drops I feel when I do have my period , I check my pad and there’s only a little bit of blood, that’s when I start to get stressed and get paranoid , well In all reality I was stressing still whole month for tests quizzes and now my body and honestly I don’t think I am but what if you know... like that’s been a thought in the back of my head.