@happyat76 I know this is an older post. BUT, I just came across it.
I've had that same pain and I couldn't breathe in. The pain felt like a heart attack. My ribs were inflamed to the point where they hurt to the touch, my breastbone was killing me. It sounds like it is most certainly Costochondritis. I went to a Rheumatologist, and it certainly was it. It still hurts me since way back in 1994 when I first was diagnosed. Some doctors referred me to a Cardiologist as they thought I was having heart issues. Now, I just take Advil and it helps when I get a flare up.
As the years go by, the flare ups are far apart...months apart.
I have not gotten to read all the replies yet, so if your condition has been diagnosed properly, GREAT!
I will read on, but just know, I cared so I felt the need to say, you're not alone.