Did you do an Urine Culture to confirm the Urine infection ? The Blood Urea & Creatinine
being normal , rules out a serious kidney
Scan of the Abdomen , with a full bladder & after passing urine , would tell if you are emptying it fully, or if there is any obstruction. If not you will need special Urine Flow Studies , like a Cystometrogram, which will then tell , what specific treatment will help you. Do remember that in Summer, because of the extreme heat, ? 40 * C + , a lot of fluid can be lost by pespiration etc.