Most ParaZapper users get these effects in the first week of zapping and they are usually gone in 3-4 days.
You have been zapping a long time just to get to this stage.
The point is not for you to buy ours. Get your dad to build you a dual frequency one using a CMOS 555 and with copper handles. I keep trying to explain. You will see and feel a difference, even after you have been zapping for months.
The schematic for a basic dual frequency zapper is on our website.