Earliest testing for STDs?

A few nights ago I engaged in what I considered to be risky behavior. In panic, I rushed to the hospital in Shanghai the next morning to test.  The tests for Gonorrhea and Chlamydia came back negative.  However I was concerned I tested too early so I went back and asked the doctor about it. The doctor said that since I did Urethral swabs the tests were accurate, even though it was less than a full day after the incident since they were directly swabbing the area that would contain the disease.  In the following days the area wasn't feeling all that comfortable.  Some discomfort and pain and a "leaking" sensation although I, nor the doctors ever observed any discharge of any sort.  The uncomfortable feeling seems more pronounced when I'm sitting rather than standing as well.  

Not entirely trusting the doctor, I went to another hospital in Shanghai and asked the same question. They gave the same answer. There is no need to wait to test for Chlamydia and Gonorrhea when doing the uthreal swabs.  They said if the test came back negative, then it's negative. They attribute my discomfort to Ezcema (eczema) that is visible in the genital area.  Parts of the scrotum and the the area in a line leading from meatus produce the most discomfort.  Are these doctors crazy? Or should I believe the test is negative as they say and continue putting on anti-eczema cream?

[Vance2335]

Well I am not a Dr, so they may know more but I have never heard of being able to pick up an infection via swab that quick. I have heard 3 days, but we recommend 5-7 days.

[GauntG]

I hadn't either but they seemed adamant about it.