Have you checked possible side effects? Or emailing your DR? It could be a UTI.

My Metformin gives me a lot of bowl movement. The Urinating is your BS is too high. When your Blood Sugar is too high , you tend to go urinate more and more until you get it lowered somehow ( Insulin or those diabetic pills like your Metformin. Try switching it if it is giving you such side affects.

It differently changes the smell of your urine.

mine does as well not sure if it is the metformin or not