I have a horse currently with advanced ringbone. Unfortunately this week the vet is coming out to see if it is finally his time to retire because he won't stay sound. This can be something very serious, or something that doesn't bother them after a long time off, from what I have found out. I'm in the process of trying to determine which one my boy has.
If you vet said they think it is ringbone, I highly doubt they would be wrong. It is rather easy to detect and the questionable part is about where it is located and fused to and how much it affects their joints. It is easy to feel, and is not something that would be casually misdiagnosed. My horse, even despite being lame right now tracks up beautifully, yet he always seems to have a higher pain tolerance and moves out when other horses would short step. I can only tell because he is dipping his head dramatically, and it is obvious the way throughout the rest of his body that he hurts. So short stepping isn't the only indicator of pain.
Some things that have helped Jake with his ringbone. I have my farrier roll Jake's toes a lot to help with break over, I have also heard that pads, or going barefoot helps with the impact as well. Though my gelding is shod on all four. I also worked him only on soft ground with good footing. I might be starting him on Previcoxx as well to help him out.