What Causes Rapid Heart Rate While Deep Breathing Along With Anxiety?

I have noticed that whenever I stretch or take very deep breaths my heart begins to race. I would say about 2-4 beats per second. Or whenever I get up from laying down, or sitting my heart also races. I know that is normal in anyone but I can feel my heart beating without actually putting my hand over my chest to feel it. it pumps extremely hard and fast. I do have palpitations here and there also. about a month ago I did meth which was obviously not smart on my part, but the palpitations started before I did it. and I was a smoker but I stopped about two weeks ago in hopes that it would maybe stop my heart rate from going so fast. I don t drink soda, or drink any caffeine, I don t smoke or do any drugs at all. Yet it feels like I m only getting worse. I have really bad anxiety also. Yesterday I didn t eat at all, except for when I had some soup, which after a couple bites I felt this strange sensation in the back of my head which creeped down to my torso, which then made me lose my appetite. It s gotten to the point where I m scared to get out of bed because I just don t want to feel my heart racing anymore. like I said I ve tried talking to a doctor but they didn t do anything about it except give me a heart monitor thing for 24 hours but apparently it was normal . I didn t want to question their expertise but I seriously doubt my heart is normal . I would love to hear what you think, please message me back as soon as you can. Thank you.