cat limps, vet finds nothing wrong

My indoor cat came out from the bedroom, lay on the carpet and yeowled. Then she jumped up and ran back under the bed, holding up her right hind leg. She hissed at me, and remained under the bed until the next day. I didn't see what happened, but think she may have jumped down from a high cupboard and wrenched the foot somehow. I put arnica in her water dish, followed by ruta, then hypericum (on separate days) She would limp to her food and water, limp to her litter box and even resumed purring. After a week, I gave her Rescue Remedy and took her to the vet. THIS IS THE STRANGE PART: She let the vet palpitate the entire leg and foot, even squashing her toes. When she put her down, she walked NORMALLY. Back at home, she holds the leg off the ground again, and won't let me masage the leg/foot (crying when I touch the foot!) After 3 more weeks, back to the vet, where she did the SAME THING.
Now 5 weeks since she was injured, and still 'lame'.
Normally a very shy cat, a ferral kitten we took in, I give Rescue Remedy whenever we go to the vet. She is gentle, never hisses or bites(prefers escape), not overweight, drools when content. She is 9 yrs. old. Any suggestions greaty appreciated!