My Dog Is Biting At The Top Of His Butt And Crying , He Has No Fleas Red Sores Are Developing, Can You Help?

Since you treated him with flea medication I assume at one point he had fleas.  Flea allergy dermatitis can start even after 1 flea bite.  He may not have fleas anymore but you may be dealing with the aftermath.  
There are other causes of dermatitis besides fleas.  Other dermal parasites are possible-like mites or ringworm.  Trauma--like an abrasion--can make a dog overgroom and cause sores.  
Dogs can also get hot spots--these are localized areas of severe moist dermatitis.  Hot spots are very itchy and painful.  Dogs lick and bite these areas making them worse.  They can become infected very quickly.
It would be best to have your dog examined by a veterinarian to determine the cause of the sores.  They will prescribe appropriate medication and pain medication.

You gave him flea meds as in like a medication, or like a topical cream or ointment? I would definitely take him to the vet and have him looked at. He may have some type of worm. As gross as it sounds, it's all too common in dogs. I suggest you take him in for a full physical with the vet. Wish I could be of more help to you. Good luck!

I have the same thing with mine. I have been told by doc.'s that it is a yeast infection and another said it was an allergy. Is it scabbing up and the hair falling out in that area? Same with mine.....Don't know what to believe An. Help but don't stop it.