Red bumps, flakiness, hairloss on my chihuahua

Question
About a week ago, I noticed my male Chihuahua was chewing very
aggressively on his backside, just above his tale. My wife and I took a look at
him and, we noticed two red bumps, the size of an average bug bite. We put a
little bit of cortisone cream on the irritated area and, kept an eye on him for
the next couple of days. We noticed that the red bumps went away but his
skin was now very flaky and crusty. We also noticed balding in the affected
area. We waited a few more days and the thick 'crust' on his skin was gone,
and now it just looks like flaky dandruff. The skin looks to have healed and
gotten better over time but what concerns us is he is still losing hair. Is this
something we should be concerned with and take him to the vet or do we
need to give it a little more time for his hair to grow back? Any idea of what
this could be?

Answer
It sounds like he chewed so much that he pulled or otherwise made his hair fall out. It should grow back in once he leaves that area alone. You might help this out by putting him in an Elizabethen Collar until he stops chewing on himself. It will take at least four weeks for the new hair to start breaking through the skin.