The other possibilities are interstitial cystitis, interstitial
nephritis,
lupus,hypercalcemia,hyperthyroidism,hypopituitarism,hypoaldosteronism,hypokalemia,renal glycosuria,Addison’s disease and polycythemia.Pls consult a urologist and get these possibilities ruled out.Since you are having lower back pain also,so kidney disease is an important possibility.
I hope that helps. Take care and pls do keep me posted on how you are doing or if you have any additional doubts. Kind regards.