Burning & itching sensation in urination

I have been suffering from disease which making a burning and itching sensation during/after urination since 6 months, some times from abdomen also, with frequent,drop drop urination, difficult to pass urine, even i already have done all the tests (like urine,blood, sonography for finding any kidney, stone problem) but found everything is normal, doctor says normal pain, but i am serious, bcoz this problem started from a day on which i got an ejaculation during oral sex with my wife (oral sex means only kissing bcoz she was pregnant) and did not wipe well after semen fall,and the second day it is started getting pain from urination and afterwards. yes this was the root cause for getting burning sensation,and now i analyse all the symptos goes to a disease called''urethritis'' found on internet. so plz focus on my points, and suggest me how to get me cured.