To me it sounds as if you have diabeties.
Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
With the symptoms you are having in one leg associated with bowel and bladder symptoms as well, one concern would be a problem in the lumbar spine, or in the nerve roots as they exit the spine (the area called the cauda equina). It sounds like your MRI did not show any abnormalities, but if your MRI was not done with gadolinium (a contrast dye) this may be beneficial, in order to see if anything enhances (basically "lights up" which would indicate some sort of problem, inflammation, in that area). Another test that may be helpful is called EMG/NCS which assess how well the nerve conduct electricity and how well muscles respond. Evaluation by a urologist to best understand what exactly is happening with the bladder (is it over-active, under-active etc?) would be useful. Sometimes a lumbar puncture (fluid removed from around the spine with a needle and sent for analysis) is needed to exclude some sort of inflammatory process. Finally, though rare, sometimes a lesion in the frontal lobe of the brain can lead to leg symptoms with urine incontinence; an MRI of the brain would be needed to exclude this.
Re-evaluation by a neurologist would be of benefit to you. If your work-up does not yield any diagnosis, then at least some physical therapy would be necessary for your leg, if you are cleared for this by your doctor.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.