First of all, you should feel SO motherfucking priviledged that answering the questions of kids desperate for help in this particular area is a subject near and dear to my heart. Otherwise, your e-mail would've been deleted on sight the way every other submission is when it comes with bad punctuation and no capitolization. Please read THIS and DON'T do that stupid shit again!
Now, onto your question since you seem so desperate. Dude, teenage girls (especially young ones like your girlfriend) have hormones running wild like apes on heroin. Your girl could be having cramps because the fucking moon was full for all anybody knows. Yes, the start of sexual activity can trigger additional hormones in the body, so it could be related to that, but there's also 500 billion other reasons she could be having cramps. I'd say, don't sweat it.
Oh, but yeah, if she has not had her period yet, sexual activity has been known to trigger menstruation (that's not all that common though, but semi-common enough to mention, I guess).
As for the abortion question. Yes, she could get an abortion at her age, though depending on where you live she might need to have her parents' permission to do so. Also, performing an abortion on a young and probably still developing womb could possibly result in her not ever being able to have kids. That's something to consider.
Yes, you are stupid. Not just stupid, but a pathetically dimwitted shithead! USE A FUCKING CONDOM EVERY TIME! Not just when you feel like it, not just when it's conventient -- EVERY FUCKING TIME!!! If you don't have one or don't "feel like" using it, then you DON'T HAVE SEX, DUMBASS! The only exception to this is when you are (a) ready and financially capable of raising a child and (b) have seen the results of your partners STD screening personally. When both of those conditions are satisfied, you may fuck your unprotected little dick off. Until then, don't jump without a parachute, genius!
Anyway, don't worry too much. If her problems persist, she should just talk to her mom (without mentioning the sex if she's smart) or another close older female who can advise her.
All My Loathing,