I won't tell you to stop worrying because I'm sure you would if you could.

Unless therapy is causing the red spots, I would go if I were you. Your anxiety can cause real health issues--not the particular one you're focused on, but it takes a toll in other ways. Telling your therapist the extent of your anxiety may help her better understand how to help give you some ways to relax (instead of going full on with exposure). You can also try other ways to relax outside of therapy--yoga is great (and I think that's been brought up before), but you may find other activities that help.

And do pursue ruling out health issues if they are distressing you to the point of not functioning. That's usually the first thing my therapist has said--not because she thought I had what I worried about but because the stress and worry was causing mental fatigue and physical issues. I like tisket's advice to study this objectively, just like a black hearted, soulless medical professional would.