Muscular Dystrophy Forum - Random electrical shocks in chest and kidney area

I apologize if this is placed in the incorrect forum.
For the past 4 years I have been getting random, sharp electrical stabbing shocks. It feels like I'm being electrocuted. It happens very quickly and then it's over. A lot of the time it happens around my kidney area, but more recently it has been starting in my left chest, particularly near my heart. It's a very complex shocking feeling that starts around my nipple/heart area and shoots down towards my abdomen on the left.

I've had 2 cardiograms and a very complex array of bloodwork tests done. No clues. One doctor even tried telling me that it's all in my head and I'm just imagining the pain! Sometimes at work I'm carrying bins and I'll just drop one on the ground because of the pain. It's gone almost instantly...just like a shock. When it happens, it'll go away for about a week or so. I've gotten them all over my torso, particularly on the left chest, and sometimes on the kidney/side area, and once it was the upper right side of my back. The pain will shoot around in random complex patterns/directions.

One doctor said it is probably not nerves because the nerves start in the spine and wrap around my torso like my ribs do, so therefore to have a pain shooting from up to down would involve a random conincidence of one level of nerves firing off, then the next level below it at the exact same spot only, then the next level below it, etc. So that seems unlikely, and he said it is most likely a muscular problem.

I work in a factory that consolidates automotive parts but does not manufacture anything. Some amount of forklift natural gas and propane exhaust, but this pain has been happening for years before I started working there.
I stretch very gently almost every day.
I am not a heavy junkfood eater, and eat a fair amount of raw vegetables
I eat a good amount of meat every day
I am not highly active but from time to time I get my heart going on an exercise bike.
I have not smoked in years.

I'd really like some help with this because it has caused me a huge amount of long term stress over the past few years because I don't know what it is.

Thanks

Alex