tightness

Hi guys, I posted a few weeks ago about getting a tight feeling in my chest but was much higher up in my chest than what I would normally experience. its pretty much right at the top of my chest. I put it down to cats as I was staying at my friends over night not realising before I went that she had 3 kittens and didn't take my blue one with me. When I got home the following day I had my inhaler and I felt ok. Anyway I went to the gym yesterday for the first time in 3 weeks and again I got the same tight feeling. Does anyone have any idea why/what this is?

Thanks in advance

Danni x