Dear Damien Caffeine can cause or worsen palpitations, so you should cut back.
Palpitations are usually due to extra heart beats.
Most of the time, in young healthy people this is not a sign of anything serious. Sometimes, though, palpitations can be a sign of serious underlying heart disease. Even more uncommonly, they can be a sign of a future heart attack. Regarding your symptoms, it is difficult for me to say whether the pains are due to gas, palpitations or something more serious. It would be best for you to see your primary doctor and have these concerns addressed.