I'm 18 years old and this is the second month i've had my period twice a month. Not only that but a few days before i started my second period i got three big cramps in my lower stomach that shot down to my clitoris. Then my period came. Now after my second period I am still getting these random cramps. I normally have my period once a month and do not cramp at all, just back pain and nausea. What could be wrong, if anything?