I'm not sure how or what happened. But suddenly my jack Russell did not want to jump on the couch or go up the stairs or jump in the car. I'm assuming he hurt his leg jumping off of something while I was out. It seems that it's his left rear leg. He is not limping he can walk even run a little but he just can't jump up on things. Is it just a pulled muscle or should I take into the vet? He tries to jump but doesn't make it and just drops down. You can see he's quite embarrassed. It started two days ago.