I hate to do this to you, but I have had only one case of head standing and it was y last discus. I kept a pair trying to breed them in a 25 gal. When all got was eggs and no fry I finally gave up. He was fine and living alone in the tank, Apparently he got spooked, swam hard into the glass and soon went nose down. My first thought was swim bladder. But it was really brain damage as far as I can tell. It lived that way for about another 6 months never able to right itself although it tried now and them.