Just started my period today and my stomach is upset and cramping really bad. what's wrong with me?

Dysmenorrhea ?: Nsaid’s, ssri’s, hormone meds, otc meds containing diuretics, warm bath, heating pad, exercise ; acupuncture are excellent for pms / period. Avoid caffeine, chocolate, alcohol ; salt. Get gyn eval to r/o underlying pathology. Consider omega- 3 fatty acids, magnesium (supplementation or through diet) or black cohosh with dr ok. Sipping chamomile can dissipate pain. Ginger helps w nausea.

Cramping: Most women have cramping during their cycle. Some have it worse than others. There are a number of over the counter medications available at any pharmacy because this is such a common problem. If this is a recurrent problem for you consider seeing an obgyn to discuss your options.