1) Trust yourself. If you feel like something is wrong, don't let anyone talk you out of it.
2) Follow through and if they won't help you, turn to someone else.
@HABS93 left his doctor who basically said the same thing yours did and found out there was/is something wrong through his new doctor who believed him. He was finally diagnosed with Sarcoidosis.
3) Anxiety - Here's a question: Are you feeling fearful with these "anxiety" attacks? If not, then it is something that is affecting your body, heart, etc.; something that you've probably been exposed to that is creating an excitotoxic reaction as
@YippeeKi YOW !! says. Try to avoid chemicals and fragrances and keep a mental diary of what you've eaten or been exposed to when you experience this.
4) Chiropractors or D.O.s or both can help a lot for rib/chest pain too so I would look into that. However, there is a lot of documentation by ME/CFS experts that our hearts are being affected so don't discount your symptoms. Here's one for instance:
https://www.healthrising.org/blog/2016/06/27/chronic-fatigue-syndrome-small-heart-disease/
or this one:
where Dr Systrom (pulmonologist) talks about pre-load failure in ME/CFS patients so don't discount that your heart pain may be from your heart.
Here's one more by a cardiologist:
with sub-titles. I only watched this until he started talking about lymph vessels being in that same area causing the pain because I really think it is our hearts that are affected but note that he said that 40-50% of his patients complain about this.
Okay, I said all that to reassure you but the sad thing is finding a doctor who knows about this stuff. That's the hard part so I'm not sure what advice to offer there. I think some people like
@Sushi have found doctors who are sympathetic to what is going on though not without having to sort through some bad doctors first, unfortunately.