What does my husbands stomach pain mean?

He went to the hospital and had a sonogram and found nothing was wrong with his gallbladder even though he fit all the symtoms. The doctors say they cannot find anything wrong. But he is also sick to his stomach! I am so fusterated because he is in pain all the time! He is dizzy and weak. He never had the best of health, and I am getting worried. Can anyone help me?