OP: I am again going to suggest that you see a specialist for Colby to at least obtain a real diagnosis. It sounds as if your vet is guessing what this is and giving him prednisone to see if it helps. While prednisone can help for many neurological conditions, the best thing to do imho is to find out exactly what it is and treat for whatever condition that is specifically. If he were mine, I would take him to a neurologist asap.
I honestly do not know of any specialist who would advise you not to come in. If a specialist got on the phone and talked to me and said that, I would consult with another specialist! That is just not what they usually do...it is imho out of line but then, I don't know. Maybe he consulted with your vet???
At any rate, I just had to post and encourage you to see a specialist. I shudder to think that your sweet Colby could be suffering.
While he is cute, seeing him fall over is not cute. It is very, very sad. It does not mean he is strong...it means something is very wrong. Of course, they all are strong and do have a will, but that does not mean they are not suffering.
If money is an issue, perhaps you could apply for Care Credit. You can apply online:
Healthcare and Medical Financing for Consumers | CareCredit™
You also could surrender him to a rescue, but I would be hard pressed to advise you on one in FL who would do right by him. If you did decide to do that, I would suggest it be with the understanding that they provide the best in terms of specialists. I have seen some rescues in your state who are short cutting on vetting and that is not something I approve of.
My thoughts and prayers are with your little Colby. I hope he is well soon.