My Husband Has A 5 Mm Kidney Stone As Revealed

My husband has a 5 mm kidney stone as revealed in a CT scan at the emergency room on Thursday. The severe pain comes and goes. He was prescribed Percuset which helps when he takes it but he is a heavy equipment operator and can't take it if he wants to work. It is day 4 and the pain is severe tonight...mostly in his back on the side the stone was found on. When is it too long to hope it's going to pass on it's own and further treatment is necessary?