sensitivity at base of tail

[finneganrobinso]

my dog has become extremely sensitive at the base of his tail - the above part! When it is touched he tucks his tail in and drops his hips so that he is almost sitting. But the most disturbing (?) thing is that he also reacts with a constant licking / chewing motion with his mouth. I am not sure if this is painful to him or not. There does not seem to be an anal gland problem as he is not scooting or anything like that, nor emitting any kind of smell. But this sensitivity has become extreme as he reacts as described above whether that area is being petted, or scratched - or even if the leash happens to touch him there. Does anyone have any idea as to what could be causing this, or what the licking/chewing could mean?
Thank you

[t.pettet]

If you can get the area shaved you'll be able to see what is going on. Could be a hot spot that he's aggrivating to the point its sore.