Dog Bumps / warts?

Question
My dog gets these bumps with white hard skin on the top of them. They seem sore when I touch them.  They come and go and heal eventually.  He's had them under his skin, not broken out, and on his pads which look bad.  He also gets them on the tip of his tounge.  They last about 3-4 months, clear up for a little while, then come back.  He is only 15months old, a St. Bernard.  
Can I treat these?  The vets he's seen here do not know what they are.

Answer
Ask to have your dog sent to a canine dermatology specialist. Also is there any possibility that your dog could be suffereing from canine gout? This is usually in large breed dogs under the age of two years old and is normally caused by another disorder which affects (sometimes) the immune system.
Not actually seeing the problem makes it very difficult for me. But Check out this article and see if it fits your dogs symptoms at all. Also, go to a dermatologist as I suggested., and I would also find another, more qualified vet to do a complete workup on your dog, immune system, bloodwork etc.
http://www.gsdhelpline.com/gout.htm

good luck in finding out what's going on with your guy.
Cindi