First of all, what do the blisters look like?  Water blisters, blood blisters, etc? 

I am not sure exactly what your doctor was referring to but I hope you received some sort of medication for it.  I also hope that he did some testing before he blirted out a diagnoses like creeping. .

There is only one term I know of in which "creeping" is used and that is Creeping Disease or Creeping Eruption.  Very similar to ringworm.  Actually is a hookworm.  Completely cureable like toenail fungus except you are working with a parasite.

Most people only associate hookworms with animals.  However, anyone who works in a vets office or farm knows that the larvae can be transmitted to humans.  They can also be transmitted by walking barefoot through river banks and the such. (barefoot through untreated yards inhabited by dogs, cats).However, they cannot live long enough in the human body to make it to the home they desire, the intestines.  (unless ingested). They are treated in humans the same as in animals, with antiparasitic medications.  Poof they are gone.

Now, before you get all panicky, if your doc did not do a skin scraping and test for the parasite, um get a second opinion or ask him what the heck he really meant instead of being so vague.  A telephone call will give you the answers. And you need some good answers if you are dealing with any auto immune disease such as RA. 

If your doctor was using his own generic term for a toenail fungus, he needs to be corrected promptly in order to put his patients at ease.  There is not need for a doctor to be vague in the slightest bit.

Let us know what's up,

Ronie