Sorry that you're feeling so anxious and down.

It is a smart thing to do, ruling out the possible physical causes of your symptoms. Did you start off with a cardiologist with your symptoms, or did a GP recommend that you go to one? IMO, your symptoms of neck pain and dizziness would be more applicable to a neurologist if you're wanting to stick with seeing specialists.

Regarding your concern that PC may be bringing you down emotionally, I think that's another valid possibility. I have had a few times when I needed to simply stick to going into the lighter forums on PC for a bit. That worked very well for me. I also arranged my time on PC so that I would end my day simply in the Games forum. That felt much lighter to me. Perhaps you might want to give that a try?

Gentle hugs sent your way. Hope that you feel better very soon.