Fine needle biopsy suggested 3 years past original treatment mascetomy side

hi all I haven't been on here for a couple of years.  I'm 3 years to the day of original diagnosis, lumpectomy then mascetomy expander chemo radio.  At my annual 6 month ultrasound/ bloods a what they call suspicious newly found lump has been found only small in mascetomy and node clearance side - first my oncologist said don't worry looks like possibly a cyst then he consulted with original bc surgeon who suggested fine needle.  I'm totally freaked out.  After all the treatments and trying to return to work neuropathy finally got the better of me.  I'm just wondering my oncologist said up to me to biopsy or to wait 3 months have another ultrasound.  Over the past 3 years I've had 3 cysts turn up in remaining breast that was suggested to do biopsy but I said no and now they are smaller and not suspicious I'm quietly terrified that this is happening again and I never thought it could reoccur in totally removed side - thoughts / experiences appreciated hugs