You should feed Bowser 15 minutes per feeding day, prefferedly after his lights have been out for 30 minutes - 1 hour, don't try to feed him multiple times a day, it will only stress him out more.
Bowser needs all the energy he can get, let him sleep during the day. Bowser is an adult frog, so can be fed once, twice or three times a week.
I feed my adult girl every wednesday and saturday, she is fed for 15 minutes and eats 4-5 prey items per feeding. Note, if Bowser doesn't eat much, you can feed him multiple times a week.
You can feed Bowser every other day if he only eats small portions.
But try to avoid stress as much as possible, because the last thing Bowser needs is added stress in his condition.
Handle him as little as possible and bother him as little as possible, and he might be able to have a happy life.
Trust me, let the doctor and his son take an imaginary rocket to the sun and forget about them, the important thing is, your saving Bower's life.