HRM post Mastectomy/Reconstruction Help? Getting wonky...

I have had good luck post mastectomy/reconstruction in that my heart rate monitor is still comfortable and doesn't seem to irritate the few remaining sensitive areas (where the dang drains were located) but I keep getting CRAZY reading?

Has anyone else with silicon implants noticed weird readings on their HRM? I will double or almost double my heart rate from time to time - like today is was showing 220 when I know from the effort I couldn't have been above the 140s. Also my HRM no longer works when I swim. It's like the signal is getting bounced or compromised?

I've tried the gel and it helps but not completely. I don't want to buy a new one if there's an issue! Anyone with reconstruction your feedback would be greatly appreciated!

(My Doctor's office was just confused by my questions)