I have had exactly what you describe too. I had it years ago before I actually got my lyme diagnosis. I felt like I couldn't actually get a breathe in. It lasted a long time from what I can remember. I even joined a yoga class because I thought it would help me be able to breathe. It didn't and at the time I didn't yet know I had lyme. It should get better and eventually it will go away. Every now and again I feel like someone is sitting on my chest, but it always passes and nothing I worry about
I know for me too the more I thought about it and worried about it the worse it made it. It's hard to relax when you think you can't breathe, but the good news is you can and you are and you will continue to do so. It's more just a feeling than something actually going on other than the lyme. Just my opinion from my experiences, but of course as with anything, if it gets worse it can't hurt to get checked out for peace of mind.