Awww! That's so sweet. It seems like you really care about your girlfriend. Alright well first of all, make sure she's comfortable. Let her lay down on the couch or in bed. Don't make her get up, and make sure she knows that if she need anything that you'll get it for her. Get her a heating pad and a glass of water or something else to drink. With the mood swings, be patient with her and remember that if she gets upset with you, that it's because of her period. Be nice and calm with her. Cuddle her if she's in the mood. Ya know, just sweet things like that to make her feel better. And if she wants you to back off and leave her alone for a bit, then back off and leave her alone for a bit. Good luck!!

Buy her some ibuprofen or aspirin tablets if she is willing to take them because trust me they work a treat for period pains. She will need about 400mg of ibuprofen, or 600mg of aspirin. Period pains are caused by the release of prostaglandins causing uterine contractions which are extremely painful. Drugs like ibuprofen and aspirin block the release of these prostaglandins, hence effective pain relief. It is nice to see that you are kind and considerate towards your girlfriend during this awful time of the month and many men don't understand what some women have to put up with. She is very lucky to have someone who cares so much. Good luck.

Definitely buy some pamprin they sell it at places like walgreens, walmart, cvs, kmart, target...it works good!