Tingling while urinating with low level pain + erection problem

[ZioMimmo]

First, I don't know is this right place to ask this question, but anyway its somehow connected.
I'm 26 and I have problem with erection and with tingling at the tip of penis while urinating or after urinating. First, I felt some kind of tingling while urinating about two years ago. I went to see doctor, did all analysis, blood and urine, and they told me that I have kidney sand. After that, my problems with tingling were occasional. During summer, I drank lot of liquid (beer, water), and I didn't have any problem with that. After summer problems again started. In last month or so, I'm going more often to toilet, and my penis started not to work properly. Now it cannot get hard and fully functional (penis is half limp). During and at the end of masturbation, while i'm ejaculating I feel tingling at the tip of penis. Sometimes I feel some kind of irritating pain (on scale from 1 to 10, it's 1) on the left side above penis (lower stomach). Previous year I had only once sex without condom and it was in April, so I think it's not connected with that. I'm drinking at least 2 liters of water every day. There's no blood in urine, no pain in kidneys.
What can it be?

Thanks for the help.