The first doctor ruled out any cardiac issues so you absolutely must accept that dx. People with heart problems virtually never describe heart pain as "twitching and bubbling." There really isn't much room for doubt when your heart is in trouble. It seems you have quite a bit of pain in your shoulders, neck and sometimes your back. These are all really classic areas of pain from work and many of us carry our stress and tension in these areas. The second doctor you saw told you this as well. And he felt no need to investigate these pains any further, which he would if he thought there was a valid reason. And one of these doctors also said it could be related to gas, which is very possible. Gss pains are one of the leading symptoms doctors treat in the ER. Gas pains can mimic some pretty nasty symptoms.
I'm not a doctor, so I can't tell you how to overcome a pain that hasn't even been officially diagnosed.
If it was me, I would start by having a few sessions of deep tissue massage to get rid of the knots which will also release a lot of bad toxins in those muscles. I'd have the massage therapist recommend exercises to keep those loose and I'd really stick to them. Then I would see a gastroenterologist to discuss the gas issue. Excess gas can be produced for a number of reason and it would be beneficial to rule out those causes.
Perhaps the muscle pain is work related and the gas is due to your diet. You need to talk about those with your doctor and the massage therapist. (Have your doctor write an order for "therapeutic massage" so the insurance will cover it)
If none of this resolves the problems, it may be time to consult a therapist to see if there is an underlying issue you're not dealing with.
Peace
Greenlydia