Often in late winter especially, I get very shallow breathing. I've been tested and they still can't seem to pinpoint the reason why it hits me then. An inhaler doesn't help at all. My doctor thought it could possibly be related to snow mold, which I honestly know nothing about
! But this past Fall, it hit again, though not as powerfully. For now it's gone.
I occasionally use steam (very carefully), drink more fluids, avoid sweets, try to avoid stress, and use eucalyptus oil. I also apply (mild) heat to my throat and chest, using a microwavable 'bed buddy' with caution (I don't want it too hot, for sure!). These things can sometimes be helpful for me, though I suspect this is just another weird fibro 'thing.'. Breathing deeply as Sherrine mentioned does give me some relief, too.
Maybe it's like Lj said, too--related to barometric changes. Our weather is constantly changing here and it's almost always a wild rollercoaster ride for my body--and any of us dealing with fibro.
BTW, welcome to the forum, kat!