This app was mentioned in 2 comments, with an average of 4.50 upvotes
For getting a better butt legit download this app
Its a garbage app and the ads are annoying but it helped me have a clear goal each day, its what got me started and i now do 100 squats, 75 bridges, and 75 lunges every other day (no weights) and have a pretty nice bubble butt (my boyfriend agrees)
this guide is fucking amazing for douching. (you should only need a fast clean) using a water bottle works fine, id say only squeeze in <1 cup of water at a time. Also i douche into the toilet personally.
In my experience any pain from anal is usually because I'm simply too tense. its really something you just need to get comfortable with over time. Also lube helps.
https://play.google.com/store/apps/details?id=com.teerstudios.buttchallenge2
I'm sorry to hear that you might have cancer. I hope your clear :)