Poor little guy.. we'll need to understand what is going on a little better. Is there a chance you could post a picture?
A few questions to help us determine what happened so we can figure out the best course of treatment:
What size tank is he in?
How often do you clean it and the % of water do you change?
Do you use water conditioner? Do you add in anything else, chemical-wise?
Is the tank heated?
What is the temp?
What food do you feed him, how much and how often?
Have you tested the water for ammonia/nitrate/ites? If so, what are the results?
Odd question, but what color is he?
Bent spines would normally come from an injury or malnourishment, even genetics.. as fish TB is quite rare. A picture would help confirm whether or not it is either of those..
The white stuff.. is it like a grey-milky substance floating around his body? Or like cottony puffs with "hairs" coming out of it?
The disintegration of the fins- are the edges of them black and flaking off, or white with cottony puffs?
Right now I would place him in a small QT container- something soap residue free and clean, 3-4 inches of water (with water conditioner)- new water, not tank water as there may be something in his tank causing this. If you can float it in his home tank to keep it warm that would be great- either tape it to the side or jimmy it with something to keep it there in place.
Until you can get a picture posted, unsure exactly what is going on with him.. that or the questions answered. Don't want to treat him for something unless we know what it is, as we don't want to cause him more trauma and harm then he already is in.