Have you actually checked him for fleas? (Push the fur the wrong way and look for black specks on his skin. The best places to look are at the base of the tail and on the belly.)
Look in his ears - do you see any discharge or redness?
I just checked him for fleas by following what you've suggested and I did not see any black specks on his skin that I could find. I don't see any discharge or redness in his ears. He was itching his ear a lot about a week ago and it was twitching but that seemed to have stopped after a day or two.
I only see the redness from his scabs that have formed under his chin, but mainly on one side of his neck.
I took him to the vet about 2 1/2 months ago and she checked for fleas at that time and said he didn't have any. Now, that I think about it, she did shave part of his chin because she saw a couple of these scab like things directly under his chin. At that time she said that it was probably cat acne.
I thought it went away, but could this be what the problem is?
I've never heard of cats having acne. This time it seems to be on the side of his neck as well and that wasn't the case before.
I was thinking of giving him a bath or possibly washing that area with warm water and mild soap, but I wasn't sure if that would be the right thing to do.
I appreciate your help and any feedback you may have. Thank you.
Thanks for the additional information. Its possible that there is feline acne on his chin, and he scratched his neck while trying to scratch his chin. The acne itself probably did not spread down the side of his neck. Other possibilities include something wrong with his ear(s) even though you can't see anything. Sometimes there can be a very minor infection, but its irritating to the cat, and causes them to scratch. Skin mites or skin infection could also cause this problem. Here is a link to a page with a chart of skin conditions in cats:
Whatever this is, it won't hurt anything to wash it off with some warm water. I wouldn't use any soap unless you have pet shampoo because human soaps can irritate the skin worse. If you have some betadine you can clean the area with that. The last step is to apply some triple antibiotic ointment (such as neosporin) to the area. Keep him occupied for a few minutes to allow it time to be absorbed. You can apply the ointment 2-3 times daily. You can also give him chlorpheniramine (chlor-trimeton) for the itching. The dosage is 0.1 mg per pound of body weight twice daily.
If you feed him out of plastic bowls I would recommend switching to glass or stainless steel. This will help if feline acne is the problem.
If the condition doesn't improve within a few days or if it worsens then I would recommend another visit to your vet for a diagnosis and treatment.
If you have further questions let me know. If this answer is helpful please click accept. Thank you.