My female had some sort of bad muscle strain winter before last. we had just moved back to New England and she had a little too much fun chasing toys in chest deep snow. She was very stiff in the hind end and suddenly could not jump into the couch, bed, cab of truck. She is OFA excellent hips and very athletic, but she was almost 9 playing like a 2 year old in snow she wasn't used to.
it took way longer than I expected for her to heal. I remember the vet saying give her time, these things can take 6 weeks. In her case her energy level was so high leash walking took the edge off so she wouldn't hurt herself by getting too pent up. (remember in her mind she is still 2)
It was a long time where she needed a ramp to get into the cab of the truck and I stacked two dog beds for her to get into the people bed without jumping.
She is 10 now and she can still leap easily into the back of my truck. I let her jump up sometimes but never down, I just think she is too old for that kind of impact.