What Causes Stomach Ache And Elevated Heart Rate?

Im 41 single mom and lately I have been stomach aches and its distended up by my diaghram, My heart races and my neck and the L side of my back is really sore I could hardly move..And now I almost blacked out when I stood up and took 10 steps. It happened yesterday to- I had to grab the counter to keep myself from falling.. I freaked my daughter out.. she is 15.