Hello, I am 19 years old female and occasionally my breathing becomes irregular and it becomes hard to breathe. My heartbeat speeds up or feels like it's in my upper chest and my vision starts to fade to pure white. Sometimes I almost black out, this usually happens when I either smoke marijuana ---which this never happened when I first started, or had heat stroke when I was younger. My hands start to shake terribly --- it also has happened when I haven't eaten enough --- or have eaten too much. What should I do?