What serious illnesses can be confused with panic attacks? what tests can be done to ensure proper diagnosis is made? never sure if i am sick or not

By you, ALL!: It's possible that your panic attacks can mimic ALL sorts of serious conditions - that's what they try to do. Drs can often see through them, but it may take tests. This is the best reason to manage panic! CBT therapists can teach you skills to do that - often w/o meds. Hints: if symptoms go away suddenly, pop from one type to another, vary up/down in severity - it's probably anxiety. Do therapy.