I just recently started having this problem. At night when I lay down on my side I get a strong urge to pee, even if I…

I just recently started having this problem. At night when I lay down on my side I get a strong urge to pee, even if I just went. It keeps me up. If I lay on my back it goes away. I even get it through out the day every now and again. It's annoying, I just want to know what it is and how to make it go away! I mentioned something to the nurse at my last check up, and my doctor said it sounds normal. There's no burning or itching before, during or after urination.