I think you likely have an infection along with possible steroid withdrawal. The taper is too fast, as you are not supposed to continue reducing when there are newly activated MG symptoms, unless you are withdrawing for a different reason.

I would think you need to go to ER, but avoid just announcing that you have steroid withdrawal. Instead, explain your symptoms and let them try and figure it out and if needed bring up the steroids (although that will probably get put in as part of the questioning).

Take care.