YOU have no business doing a drawer test. You have no idea what you are feeling for and can do more harm than good.
It could be an ACL, coudl be a pulled groin muscle, could be bad hips. Could be many things.
Keep him on crate rest and call the vet tomorrow.
It's MICHELLE, scarfish! My name is MICHELLE! Jax is my DOG!
~The strength of one's opinion should not exceed their knowledge on the matter~