I am having mild chest pain (a few days now), muscular?, and an mild bother in my right arm. Am I having a heart attack? I am 45, weight 170

Possibly, but... Chest pain radiating to right arm (or left or back or jaw or upper abdomen...) coule be cardiac in origin (among others, such as muscular, stomach, organ near diaphragm such as gall bladder or even has in the colon. I've seen too many widows whose spouse was 40 something y/o female (or male) had similar symptoms. Have it checked, preferably with your primary care physician (internist better).
Unlikely. Typically a myocardial infarction (heart attack) is a discreet event that takes hours to evolve, not days. Having said that it is possible to suffer a heart attack and develop a condition know as pericarditis, which is an inflammation of the fibrous sack surrounding the heart - a condition which may result in pain that lasts a few days. Thus the best approach would be to see a md and check an ekg.