Lower-middle back pain

Hi there

I am an Australian Kinesiologist/sports therapist

Your problem is related to a muscle called the Psoas. This muscle runs from the lumbar section of the spine, to the upper legbone (Femur).
During periods of dehydration this muscle becomes tight and pulls the lumbar part of the spine foreward and downwards causing imbalance at T12-L1 joint, leading to subluxation. I don't think you suffer from a misalignment (yet) but this tightness could lead to it.
Massage a point 1 inch above, and 1 inch to each side of the navel, and massage the spinal process at T12-L1 (just above the waist) with the knuckles. It will be sensitive! Also lightly hold a point at the center back of the skull, just above the neck for 20 to 30 seconds. Do these corrections at least 6 times a day, and drink heaps of clean non-chlorinated water. You could have an absorption problem because of an allergic reaction to chlorine. This is a common, although not recognised, problem. Chlorine is a poisonous substance, and foreign to the body. Rotary exercises will be of benefit as well.
Stand with legs spread and rotate left and right to the maximum position, and perhaps slightly beyond that.

Good luck

Hans