I am not exactly sure of what you are describing. I do get a burning feeling in my lower back, which I assume is due to my herniated disc. Skin sensitivity can be neuropathy, that is when a section of skin feels weird-tingly, sensitive, buzzing, etc. It's probably best if you mention it the next time you see your doctor.
Be joyful in hope, patient in affliction, faithful in prayer (Romans 12:12).