For the past few days I have been having a faster heartbeat and shallow breathing. I was diagnosed with asthma yesterday. I also have costochondritis. I have checked my oxygen and pulse rate periodically. My oxygen level is 97 or 98% and pulse is 72-76 on average.. I am freaked out that I have a heart problem or I'm not getting enough oxygen even though the oxygen level checker reads 97 or 98. This worrying ia making me think I have severe issues and I should get immediate medical attention.