Cat w/ bald spot and bumps?

Question
Dear Dr.Carozza,

I am so happy to find this site of caring, pet-loving vet volunteers to answer my question!  My cat, Shadow, is a long haired cat.  I recently took Shadow to the vet because of a bump under his chin and a bald spot near his tail, on his back.  He also has a lump inside his mouth.  The vet looked at him quickly and diagnosed him without problem.  She said something about him having a reaction to himself?  She prescribed antibiotics which I have already given him all of and anti-inflammatory liquid medicine.  It's been two weeks and not only have I not seen a change, I fear it's gotten worse.  The bald spot on his back seems larger (a little bigger than  the size of a quarter) and is pink.  Under his chin, I believe the bump is gone but it looks all red and like its not healing.  The lump/bump is on the side of the inside of his mouth on his gums and its gotten bigger.  My vet said all those things were related and they all were a reaction to himself.  She said that it would take time but they would go away on their own.  My question is first, do you think this diagnosis is correct?  Have you seen other cats with this problem?  If her diagnosis was correct, can you explain it to me in detail?  How long should I wait before taking Shadow back to the vet again?  Can you think of any important questions to ask my own vet?  I really appreciate your guidence as I am worried about my cat, Shadow is the best cat an owner could ask for.  Thank you very much and happy holidays.

Answer
Get a second opinion!  -now!  Preferably with a cats only vet.

a lump in the mouth should have been better looked at or at least a fine needle aspirate for cell samples to make sure its not cancer.

same with the chin.

did your vet check his anal glands? many cats will lick themselves bald back there with anal gland problems.

ps: I am not a vet, I am a licensed vet tech. :)-cats only clinic.