I'm so glad to hear your baby is doing well.
My last foster a gsd bloated and it was the scarest thing I have ever seen.
After his surgery it was a very slow recovery, he got 4 small meals a day (nutro senoir dry) and some canned food from the vet that was easy on the tummy. He got no treats for a few weeks and no rawhides or pig ears ever again my vet said. His exercise was very liminted and we had to keep things very quiet for about a month.
He was 2 yrs old and very hyper and untrained we had only had him 2 weeks before this happened so when he was free in the house I kept him tethered to me with a lead so he didn't run and play with the other dogs. We were also told no execrise atleat 30 min before or after a meal and no water as well before or after play. We eventually went to 3 meals a day for himand this worked out well, even tho he was only 2 the vet said to put him on senoir food because it ahd less fat and this was easier for his system we jsut had to increase the food so he didn't loose weight.
He recovered very well and 2 months later he went to his forever home, I get updates often and he is doing great and now enjoying his obedience classes and new family!
I am so glad that you got your baby to the vet ontime and that he is doing well. Good luck and god bless