For the past week my sex drive has been through the roof, i've had a light dull cramping in my uterus and a tight feeling. what could it be?

Fertile time: You may have variable libido through your cycle. I'm not sure what the light, dull, cramping, uterine tightness is; but it most likely is related to hormone fluctuations through your monthly cycle. One theory is that women may have a higher libido during their fertile period in order to optimize the chances of achieving a successful pregnancy to perpetuate the species.