Hmmm, well, it might be something serious so I would suggest taking her to the vet to get her checked out. But if everything is alright, here are some things I would try.

Paw Protector wax works as an invisible boot, so it may help you a little.

If you have, here are some things you could try:
Mushers Secret
http://www.petsmart.com/global/product_detail.jsp?PRODUCT%3C%3Eprd_id=84552444180 6929&FOLDER%3C%3Efolder_id=2534374302032062&ASSORT MENT%3C%3East_id=2534374302023689&bmUID=1149175874 985&itemNo=1&Ntt=paw+tectors&In=All&previousText=p aw+tectors&N=2&Ne=2 ]Doggy Socks[/URL]
Doggy Hiker Boots
Paw Wax Paw Protector

Hope I could help...