Cramps and feelings of a full bladder

I'm 6w3d with twins and have been been feeling well except for nausea. This morning I experienced some crazy cramping, mid lower abdo. It took my breath away and was on and off for maybe 45 mins. Felt like period cramps. I had a bm and felt better but now my tummy feels so tender and bloated. When my bladder fills up it hurts until I pee then I get relief but it is still tender. Anyone else have a similar experience?