I have been having burning while urinating & a yellow discharge coming from urethra what causes other than a std could this be I hope its not?

Urethritis. Most of these symptoms I'm afraid are STD related. Gonorrhea and chlamydia come to mind. There are of course others, but these would be less likely. In some cases, you could have a problem within the urethra itself - but I think 'common things are common' and you should get checked for an STD. The good news is, these are curable, and you can go back to normal healthy living after treatment. See MD.