Kidney Stone ~~ unsure if it may be obstructing

[avalongod]

Hello:

I have a history of getting uric acid kidney stones since age 16 (I tend not to drink enough).  Between ages of 16-29 I probably passed 7-9 1-3mm sized uric acid stones.  Between 29-35 I got better about forcing myself to drink and avoiding soda and had no further stones.  Aside form the 1st 2 stones, most of the stones passed with only some mild pain on the side and didn't require medical intervention.  Most stones passed within 2-3 days.

Now (at 35) I just had a kidney stone begin to pass.  This began 1 week ago, with familiar kidney stone symptoms (pain in one side, pain when urinating).  As with most attacks the pain was not bad, I made an attempt to drink significant amounts of water to help it along.  for about 2-3 days, as usual, I felt mild symptoms lettng me know the stone was still passing.  Then the symptoms stopped.  I waited for the stone to appear in my urine, but have not noticed anything.

My question is, how concerned should I be that the stone may have become obstructed and is blocking the kidney?  I have absolutely no symptoms...no pain or fever or anything to indicate infection.  Frequency of urination is normal.

As I remember back, I suspect once or twice before at least, the stone seemed to "vanish" and I never noticed it passing, although in most incidents I felt it passing in the urine stream and could see it.  

At what point should I be concerned and be tested for obstruction?  How long can an obstruction go before damaging the kidney?  Would an obstruction cause any symptoms?  Can a uric acid stone dissolve?