I found a lump on my lower back more to the side between my rib it hurts me at times specially when I take deep breaths. Is nickel size. Should I worr?

See a doctor. You should have this mass examined by a physician. Although more than likely it is a benign mass, this can only be ascertained during a full physical examination.
Get it checked. Odds are this is a benign fatty growth but i would have your doctor check it out.
Hard to say. Most commonly these can be lipomas or cysts but it needs to be examined by a physician to help figure out whether this may be something more serious.
Get examined. Any problem with breathing should be evaluated. History, especially of trauma, is important. Your medical conditions need to be noted and diagnostic imaging may be required.