anyone got any advice?

Never in the day but often at night when I go to bed my breathing sometimes is very heavy for say 30 mins to an hour and it's a bit of.l a struggle to catch a proper good breath and then it gets me really worked up. Does anyone know any calming tips or what it is wrong with me or if you get it? I've been to the doctors and did have mild anxiety tablets but they just calm me down but don't stop the weird breathing