Hello, my name is Dr. Farwell. I will try to help answer your question about Hondo
Sorry to hear he is so miserable
He might be having some sort of allergy (with flea bite allergy, they will focus around their backside). The licking also creates a secondary skin infection many times.
Dogs also have 2 small glands (anal glands) which can become infected/impacted. Definitely a good idea to have him examined tomorrow to get to the root of the problem.
If the anus is really red, a mild over the counter hydrocortisone might help decrease the itching. However, anything topical he will likely lick off unless prevented from doing so. I know it's hard, but if you have an e-collar (from a previous surgery or something) available, it might be wise to have him wear so he cannot further irritate the area until tomorrow.
Your vet will likely check his anal glands (make sure they are not impacted/infected) and may put him on oral antibiotics/anti-inflammatories.
Do you have any further specific questions/concerns?
Thank you Dr......when I put vaseline on he did lick that off. No more thank you
Okay, hopefully this helps