What Causes Sharp Stabbing Pain In Back?

My husband is experiencing sharp stabbing pain in his right side. At first it was toward the front but now is more in the back - Kidney? - area. He said if he puts pressure on it it feels better. He is not usually a complainer and the fact that he is worried scares me too. He also has HepC. This started this after noon. Eased up then returned worse than before. Should he go to the ER?