And I am finally getting around to repsonding to your comment...
Yes my mystery limp has gone away. The vets told us that it was likely caused by the early stages of arthritis in my ankle and gave us some pain meds for us on an as needed basis. I started limping on my left rear leg as well but now that has cleared up.
What did we do?
I lost weight- I weigh about 22 lbs now, down from 27. Mom wants me down to 20 and we're working towards that! I take a glucosamine/chondroitin supplement (see it HERE) and a multi vitamin everyday. That has helped me immensely.
After 4 weeks of taking the supplement my limp has gone away and I am back to my old self! Mom is happy, I'm happy and life is good!