I have a burning sensation midback (approx where your bra would fasten) and to the left, what could this be from?

Depends: It is not feasible to provide a definitive opinion without examining you. If you changed bra recently and the new bra has a metal clasp, you may be allergic to the metal. Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.