I saw my doctor last night

I called my Doc about the swelling in my leg and chest pain. He looked at it and doesnt think its a clot. He also said that he has been inserting IUD for over 20 years and has never had ANYONE get these side effects i have explained. he thinks I may have some autoimmune disorder. He did say that it COULD still be the IUD, he wont completely deny it, but its not very likely. I am just really scared. My chest pain is still there today. I am just doubting that my problems are from the IUD now. I have always been healthy and im only 27 years old. I just dont know what to do. I dont want to go through all these medical tests if I dont need to.