@naiviv, I believe that @mallika58 and @rtv have experience with radiation-induced proctitis. I added your discussion to the Cancer: Managing Symptoms support group as well.

Mild cases of radiation proctitis may not require treatment. Sometimes, however, radiation proctitis can cause severe pain and bleeding that requires treatment.
Here's some information on treatments from Mayo Clinic https://www.mayoclinic.org/diseases-conditions/proctitis/diagnosis-treatment/drc-20376938

Have you had pain and/or bleeding? What treatment(s) have you tried?