Angi, I don't have a clue except it sounds joint related possibly?  Have you tried giving joint supplements?  I remember you posting about the hair and I thought the same thing about it tripping her.
 
Hey - you closing on a house?  Cool - is there lots of extra room for foster kids?

  Hope the closing all goes smoothly! 
Do keep us updated on what you find out and I sure hope it's nothing too serious!