Experiencing fainting spells after sitting for 20 minutes, which is sudden. It gets resolved after 30 minutes of lying down. This is associated with nausea, diarrhea, body getting very cold and sweating. I work in the night time. I am suffering these fainting spells since childhood, but at that time they only come when I stand for 10 to 15 minutes in sun, but now these are coming even after sitting. Two day's back I experienced fainting spell and today I suffered the same. There is pain (pinprick) in my ribs on sides on left and right side. Also getting shoulder pain and chest pain very rare. please suggest me what needs to be done to find out why it is happening.