Hi am experiencing lower back pains and pain on lower left breast including chest and difficulty in breathing after walking on stairs..might it be kidney failure or heart desease?

Dr. or ER can check: The more common causes of lower back pain include: back muscle strain, back ligament sprain, arthritis, urine infection, kidney infection, kidney stone, tumor in the spine or kidney or other places, fractured vertebra, fibromyalgia, other bacterial infection, etc... With such a long list of possibilities, a doctor needs to evaluate. Worrisome chest pain or breathing problems is an ER emergency.