Miscarriage or weird period?

So this is about my friend NOT me! But she does have sex not all the time just once in a while with her fiancé as they tried waiting for marriage but as you all know EXTREMELY hard to do especially when you’re attracted to that person lol anyways they do the pull out method and he always pees before round 2 and he’s very careful as from what she’s told me.. anyways she said she had cramps and passed along this weird clot and she’s wondering if she was pregnant and this was a miscarriage, she got a negative test but I told her it could be just a weird period clot or it could have done all that due to some meds she’s on from having shoulder surgery. Any comments are helpful and did this happen to any of you ladies?