What Could Be Causing Severe Stomach Pain That Radiates To The Back, Ends In Vomiting, And Persists At Night?

A couple of months ago I started getting severe stomach ache that shot through into my back and would only stop after vomiting. This has happened twice in the last two months. For the past week I have had a not so severe constant stomach ache at night that ends in me vomiting which stops the pain. I can be doubled over in pain for hours and leaves me unable to sleep. It’s always at night. It has started again tonight and I’ve just been sick but the stomach ache is still persisting.