Some formulas have very little iron or none at all. Most doctors recommend using an iron-fortified formula. Some formulas are made from soy milk instead of cow's milk. If your baby seems to be allergic to formula made from cow's milk, your doctor may suggest using a soy-milk formula.
CIP (Congenital Insensitivity to Pain) is a disorder where a person cannot feel pain. CIP can also lead to CIPA (Congenital Insensitivity to Pain with Anhidrosis) where the body cannot feel pain and it cannot perspire (sweat). CIPA almost rarely ever developes from CIP but there has been cases.
In most cases, it is not due to a serious disease or serious back problem, and the exact cause of the pain is not clear. This is called nonspecific lower back pain. The usual advice is to keep active and do normal activities as much as possible. Painkillers can help until the pain eases.