I am having extremely bad pain in my lower left stomach. also my back is a little achy. what is wrong?

Back & abdom pain: Anytime we see pain in the abdomen we have to consider that the pain is coming from a source in the back - spinal nerve origin or a "pinched" nerve. We also have to consider a process such as peptic ulcer, cancerous tumor, etc, which can radiate as pain to the back. I recommend to discuss with a primary care physician.