I am in NO WAY saying this is what is wrong with your boy, or that you should administer this medication, but since you asked...
Vitamin B complex. But I caught it early enough that the feed store variety was sufficient (although it was a gamble, even in my case) If it is not caught VERY early, you will need the higher dosage formula that only vets can provide, plus other medications for supportive care.
Blindness, uncoordinated eye movement and stumbling are all signs of neurological problems, and advanced illness. (the cause can vary greatly though, which is why you need to call the vet)
Edit: all that being said, it sounds like you are dealing with something else
Vitamin B complex. But I caught it early enough that the feed store variety was sufficient (although it was a gamble, even in my case) If it is not caught VERY early, you will need the higher dosage formula that only vets can provide, plus other medications for supportive care.
Blindness, uncoordinated eye movement and stumbling are all signs of neurological problems, and advanced illness. (the cause can vary greatly though, which is why you need to call the vet)
Edit: all that being said, it sounds like you are dealing with something else