NGU is caused by a multitude of bacteria that are non gonocal. Meaning, it's urethritis not caused by Gonorrhea. So it could be Chlamydia, Ureaplasma, M Gentitalium, Trichamonas, and then there are a whole host of other bacteria that can cause NGU that are not tested for or are not detectable. The fact that you received oral sex only means there is not a hight risk for most of the bacteria I listed. Typically treatment with Doxycycline or Azithromycin will resolve the symptoms. Take Grace's advice and abstain from sex until you are seen.
you shouldn't be having sex until you've found out what is going on and have treated it.
ngu and prostatitis usually are not contagious but avoid sex since you don't know what is going on.
Does my partner have to worry.
nope. it's not effective for most of the causes of genital infections.
Should the cephalexin help get rid of either.
most likely it's ngu but it could be prostatitis. see your provider this week for an exam and some basic testing.
you can contract std's from unprotected oral but the risk of such is pretty low. we always recommend protected oral so that you lower your risk as well as save money on testing and don't have reasons to worry. :)
grace