Kendra, Don't jump the gun! What is in your lungs could just be inflammation. Wait until the experts tell you what is going on or you could drive yourself nuts. Sometimes it is hard to see a thymoma on a CT. I've known people who have had one with a negative scan. It's good the experts think it's fine though.
I am very glad you are tolerating the Mestinon. It's not a perfect drug though; you still have to take things easy.
Annie