Help!!!!πŸ˜­πŸ˜­πŸ˜­πŸ˜­πŸ’¦πŸ˜»πŸ€€πŸ˜

How come when me and my bf f**k my legs start shaking and start to cramp up and I get uncomfortable... the sex is good the best I’ve ever had but it’s annoying because I have to keep making him stop so I can move to try to find a comfortable position...