I'm sorry to hear that you can't have the full dose of your medicine, but there are situations where medicines, while helpful, have side-effects that are not good. It's also a sad fact that sometimes doctors take a while to find out what is causing an illnesses and decide on a course of treatment.
For the stress thing, and don't laugh at this, studies have shown that having a stuffed animal of some sort can often relieve stress. It's something to do with the benefits of having some real object that you can hug. So go find a lil stuffed animal critter that you like the look of and give it a try. What have you got to lose?