You never treat with medications unless you know what the fish has. The only thing my fish ever get is a PraziPro to make sure they have no worms and it's very mild for them and only takes one treatment.......like once a year.

I would do a water change to get the medication back out of there, lower the temps of 82-84 and maybe not do so many water changes. Baby Discus need water changes a lot but not so much as they get a bit older. Sounds that he/she is guarding that spot. Not sure what the jerking is but my angels do that when they are bickering with others. I hope that's all it is.

I also never kept Discus personally.