Get this tightness in middle of back makeing it hard to breath white sleeping?

i do have asma bu this has been recent ( with the tighness in my back) i have had asma for a couple of years now and i never had this problem b4 and i also gain alot of weight in a sort perios of time but i do not look like i have gain that much wieght i sure dont fee like it the scales shows i have gain 35lbs less than 3 month and i do not see how this is possible i do nto think i am pregent i have had my periods bu they are alwasy late and unusally ne advice?