At 48 grams recovering from a probable prolapse and under going daily shots of anti-biotics for 2 weeks I would follow the vets instructions to the letter. If he/she advised you to tube feed the animal it is likely because your snake may be too weak to even eat on it's own at this time. Signs that can't be assessed over the internet such as a wobbling head, loose skin along he lower 1/3 of the body that is starting to separate from the muscle, etc. are things that a vet looks for in order to diagnose dangerously severe malnutrition which often requires tube feeding for extended periods of time.

If your snake is severely malnourished, you will likely have to tube feed until the animal is healthy enough to be able to try feeding on it's own.

Warnings on the internet to not tube feed should only be directed at animals that "should be" healthy enough to be able to eat on their own ... my fear is that your vet likely assessed that this animal is not.

Keep in constant contact with your vet and good luck, you've got a bumpy road ahead.

-adam