Discriminated Against for Being Disabled at Work

Got sent home from work on my second day because they don't want anyone at the registers and I literally am physically unable to walk for longer than a few minutes max at a time. Told them I can't do that and they said I have to regardless of being disableddisabled and every single Spirit Halloween was like that, despite the last 2 I worked at telling me I'm not allowed to leave the registers and not that I can't be at them. Like am I just supposed to 𝙣𝙤𝙩 be disabled at work? I can't just turn off being disabled 🙄 Like I literally can't leave my house without knee braces on just so my knees don't go out under me. The insides of my knees fucking grind when I walk, I can't walk nonstop for hours unless I want to be unable to walk at all for a fucking week again 🤬