Baby movement..?

Julianna
I'm 21 1/2 weeks & I usually feel my baby very active all day & can even see her head bulging on my sims chat ones but the past few days I haven't felt her move as much she still moves some but not as much & I've been having bad back pain & cramps on the sides of my stomach & abdomen. I tried a hot bath with bath salt that releves aches & pains & sleeping overnight & nothing these side cramps are really hurting idk what to do?