Hi My Husband Has Been Having Pains In The Upper

hi my husband has been having pains in the upper middle part of his stomach that wakes him out of his sleep and is only at night.... it has been 2 nights and im here with him at 3:12am in the bathroom.... he says the pains are unexplainable & "kind of goes away" when he is in a sitting position.... it hurts him so badly he just tosses and turns & balls up.... is this something to worry about and what can it possibly be?