What Causes Horrible Pain In Chest, Nausea, Sweating And Gas?

I get a horrible pain in my chest like a knife going in. I feel nauseas, I sweat & I sometime pass out. I feel like I m having a heart attack. I went to the emergency room to find out it s gas. I watch my diet & don t eat spicy foods. This started 30 years ago. What can I do to prevent this? I do take protonix but it apparently it doesn t work. Any suggestions?