you probably just have a urine infection nothing STD or of great concern just go to your docs who will give you anti biotics that will soon clear it up !!
Well, my first thought is that if you have only urinated 3 times in 48 hours, perhaps you are dehydrated, and need to increase your fluid intake to several glasses of water a day.
Did it start immediately after sex? If it did, its not an std. You wouldn't get symptoms that fast.
If it persists with increased water, you should follow up with your doc.
AJ