I highly doubt anyone on this forum, as knowledgeable and helpful as they are, can do better for you than if you take your pet to a qualified vet. There are numerous things that could be causing this issue, from a bacterial/fungal infection to trauma induced nerve damage. And the only way to get a definitive answer is to take him to a vet. A vet consult is not always expensive, and they can usually do much more than just give an animal antiBIOTICS (antibodies are naturally produced within an organism).
I personally own over 20 reptiles, 15 of which are snakes, and have taken almost every single one to see a herp vet. As a matter of fact, I was just at the vet today, for a fairly inexpensive, but very necessary check-up.
So please, don't just "accept" that your guy has no feeling in part of his tail, find out why. Do what is best for your pet, not your wallet. It's a tough decision, but responsible owners are not penny pinchers when it comes to their pet's well-being