What might help my increased urge to urinate?

Hello doctor,

I am a 33-year-old male with no medical conditions. I am on Propecia 1 mg for hair loss, and I have been on it for the past three years. Six months ago, I started getting an urge to urinate more frequently. I had a feeling of my bladder getting full. The urge was not that strong, and I could easily hold my urine for hours if I had to. The symptoms lasted for two weeks and then went away on its own. A month ago, I started having the same symptoms. The feeling of my bladder getting full has returned. There are no issues with the stream. Everything is normal. But, this odd feeling is just annoying. I find it hard to sleep with this strange feeling. It just feels weird around the groin area. I do not urinate more than once at night. I have found it hard to sleep ever since this started. The doctor gave me Valium to help me sleep. I have taken 2.5 mg of it the last two nights. This has not helped me sleep, but I find the primary symptoms slowly disappearing. The doctor told me I have an irritable bladder. Has the Valium relaxed my bladder or was it all in my head? I have had multiple urine analysis and STD tests that were all negative. A full blood test and liver and kidney function test were also normal. My prostate exam was normal. A KUB done was normal too.

Thank you doctor,

I apparently cannot take Valium for a long term. Is there anything natural that I can take to relax the sphincter muscle?