Pain!?

The last time or two my bf and have had sex I get this pinching type pain up near my left hip. The first few times I could t continue it was so bad but I just thought maybe ihe just hit a wrong spot or it was the position, but last night we decided to take things slow just cause I was nervous about the possibility of pain, but it still happened. The pain this time wasn't as harsh but it was sti there. But afterwards and now the day after my hip feels really tight and the back of my knee to my ankle has pressure and dull pain.