My kitten has a bloody butthole and runny stool, what can I do?

I took him to the vet two weeks ago due to this issue as well as bad constipation. I brought up that I thought it was minor rectal prolapse. She disagreed and said that it was just due to straining from his constipation and gave me medication as well as ointment.

It should be noted that this vet is wonderful, specializes in cats, and has never been wrong before. After about a week his bum did look better and his stool returned to normal so I stopped his medication and ointment as instructed.

Now he’s suddenly having runny stool and his bum is as bad as it was before and looks bloody and painful. I’ve restarted the steroid ointment but am unsure of what to do now. He has a check up in four weeks but is also getting fixed in two weeks at another vet and I’m worried about getting him fixed with this issue.