"My back is not feepng well" or "I have back pain" are both ways to describe having a sore back in Engpsh. You could also say "I have a bad back" if you have chronic back pain or other ongoing issues with your back. If you are experiencing more severe or acute back pain, you might say "I have severe back pain" or "I have a back injury." It is always important to communicate any physical discomfort or pain you are experiencing to your doctor or healthcare provider, so they can help you manage and treat it.