I feel you I had difficulties taking a breath...turns out it was my lupus I got diagnosed with costochondritis and got diclofenac cream prescribed.

I had the same issues but I can't take Motrin because it is an allergy for me. I have been taking celebrex or the occasional Vicodin also topical pain relief meds for the chest area. So further testing showed shrinking lung syndrome. My suggestions are to follow up with a lung specialist. They also conducted vocal cord testing and saw that I had some abnormalities there that were causing me to breathe a little differently. I already had pleurisy and it was a little exacerbated. Those issues combined created the feeling you expressed. I hope some of this advice works for you and you get some answers.

I've been getting these recently and I thought it was the Lupus - I don't feel so alone - Glad the question was asked

It was pleurisy for me. I couldnt stand up straight or take a deep breath without pain.

I had that same feeling and was diagnosed with pericarditis and paracardial effusion and was put on colchicine which helped immensely! Good luck!