Doctor, for the last few days, I have had signs of left chest pain, when I sleep on my left side, my heart beats very strangely. May I ask what's wrong with you?

Hello doctor, I am 44 years old. A year ago, I had chest pain, shortness of breath and had to sit up straight to take a deep breath, but within a few seconds, this phenomenon no longer appeared. Earlier this year, I saw that phenomenon appear again, every time I had trouble breathing, I felt it spread to my head and salivated. The doctor told me this phenomenon is caused by the heart? I hope you can answer me, thank you doctor.