It is difficult to be able to give an opinion without being involved in your care. It may just be a bit of swelling following the radiotherapy but I would check with your doctor when you have afollow-up appointment. If this is not due to happen in the next few weeks you could get in touch with your specialist nurse (if you have one) or get your GP's opinion. You probably need a rectal examination to check that all is as it should be.
Try not too overthink it for now. It is still early days since you had treatment and the area is probably still recovering. It is however always a good idea to have the area checked if you have concerns even if it is for peace of mind.
Do give the nurses a ring on the helpline if you would like to talk things through.
The number to ring is Freephone 0808 800 4040 and the lines are open Monday to Friday 9 am to 5pm
