just that you have been in the hospital should be enough to get a medical visa. They will want to know how long you are going to be treated and that you can support yourself. You may not be able to work if you are here on a medical visa or rather if you don't have a work visa
I would go to immigration and ask them to see you without waiting as you are too medically fragile to wait. If you are out of the hospital they will say you are well enough to meet with immigration.