I've had falls since my left lrfa, dr say he went deep in muscle&muscle is laying on nerve& will get better in 3w but he did no test, is this right?

Yes: It comes down to anatomy (where the nerve enters the muscle vs the incision site) Swelling will take a while to die down. Denervation due to nerve injury would not be detectable by EMG until 2 weeks minimum has lapsed. Swelling associated with the injury and subsequent surgery would preclude getting a good look with MRI for some time. You can isolate the nerves in surgery.