Apple Watch Series 5 ECG Not Working

For the last few weeks and I use the ECG app and hold the finger against the crown as indicated I get very jumpy and inconsistent ECG readings. It will jump all over the place and count down from 30, 29, 28 then jump back to 30 over and over. I have cleaned the back and rebooted the watch several times. Any other suggestions to get ECG working again? I have owned it for less than a year and ECG worked fine up until a few weeks ago.