Reglan and stomache pains

I went into the hospital for stomache pains. The nurse came over with an injection and said " this is a little some thing for the pain" I then asked what it was and her response was " it's sort of like pepcid ac" About 5 seconds after the needle was put in my arm i couldn't breathe, i started crying, couldn't talk and my body was uncontrollably shaking. I even had some trouble hearing. They gave me Benadryl to reverse the affect and it took almost 45 minutes for my body to calm down. Later learning about this drug I feel that giving it to me on that day was a severe measure, my pain wasn't unbearable it was pain that came and went .