thought maybe it was IBD, possibly.
in any case they gave us an antibiotic for the little guy to inject under the skin.
That part right here would make me re-evaluate using that vet if he thought IBD was the culprit I do not see why he would prescribe antibiotics (would not help anything in that case).

I don't understand why a vet would prescribe an antibiotic without any diagnosis either

Anyway do other animals aside from spiders wobble? Yes while rare it can happen, neurological issues can also be caused by things such as the animal being over-heated for a certain amount of time, toxic exposure etc.