Can gradual and mild pain in left shoulder, arm, forearm and between shoulder blades that lasts for 2 months be a symptoms of heart attack in 22yrs?

No: This sounds like musculo-skeletal pain, almost certainly unrelated to the heart, and would have no implications for future heart trouble.

No: Heart attacks are more sudden and acute. It is unlikely to survive a heart attack that would last 2 months. Usually, heart attacks are in older people and present with sudden symptoms that become severe and without urgent treatment leads to further deterioration. Please, discuss with your doctor.