you know you don't have to explain why sometimes you need assistance with walking and other times you don't. We all have good days and bad. I once got so feed up with people making little comments, I stopped someone and asked them if there was a problem. They of course said no. I said well its not polite to make fun of people in pain and I really don't appreciate it. You need to pull the coach aside and explain to them that some days are easier then others and give them a RSD a card from the RSDSA website.
I agree SSDI will look at your functional capability and if you use something to get around. They will also look at your pyschie.