Hello. Im 17. im about to start my period in about 3 weeks. i usually have slight cramping about 2 week before i start, but recently ive have very extreme cramps, more painful than ive ever had, and ive been waking up in the morning and in the middle of the night nauseated, ive had to watch what i eat because ive been getting sick from some things. also, certain smells have been making me feel very sick. ive been losing weight because of it. ive also been having very bad headaches, back aches, and joint pains (remember im only 17!!!). when i feel sick and im hungry i'll eat saltine crackers. i have not been sexually active for almost a year, so im not pregnant . ive never had this happen before i start my period before, just cramps, cravings and the occasional mood swing day. any ideas?