A couple weeks ago I had a resting Heart rate of 125-130 and one night it was even 145-150. Then it finally came down and spent a few days between 110-120 which is about my average then the last 2 days it's been between 89-105 which is low for me so I was really happy but now it's suddenly back up to 115-120. Which is my normal but it upsets me because I was hoping the lower numbers would have stayed. I haven't done anything different at all. Haven't really felt any better or any worse. What could be causing all the fluctuation? Virus? Bacterial infection? I'm lost.