The past few days I've been noticing a clear discharge from my penis. Its not much, and its generally clear and rather watery. Now and then I may feel a tingle in the tip of my penis, but otherwise there is no burning sensation, no soreness, no increase in frequency of urination.

I've recently been tested for the full-round of STDs 2 weeks ago, and everything came back clear. I have not gone in for the 'offical' results feedback yet - but have called in to get my results and was told nothing was abnormal but will be going in for a follow up anyways to discuss this with my doctor.

Just wondering what the cause of this could be if not an STD?

There is a history of kidney stones in my family, and I have had UTI's in the past.

There has been a few times I've noticed blood in my urine / or had burning while peeing and gone in to get it checked out, and usually get the "UTI's are very uncommon in men" speech, get tested for an STD - and everything comes back clear - could a possible kidney stone be a cause of this?

I have noticed occasional pain in my stomach - some times rather sharp stabbing pain which has made me sit down and stop before until it's passed, could this be related?