I feel bad

It's dangerous, the main reason we as humans need to feel pain It's because our body is telling us that something is wrong

For example the main issue rn it's him doing nothing about being sick, he doesn't feel pain but it doesn't mean his gonna get better

While it good not to feel pain, it actually dangerous not knowing where you hurt. What if you have been hit by a bike, and then you get up coz you feel nothing. Next thing is you died from internal bleeding coz I don't know u hurt from the hit

lol with someone weak like Jerry his organs can be shutting down in his sleep and he would be none the wiser

You should read Fire After Rebirth. It is not only a good read in and of itself, but the main character has CIP (Congenital Insensitivity to Pain), and shows exactly what can happen to a person who can't feel physical pain.