Welcome to the forum. Thanks for your question.
Your own analysis sounds pretty much on track. I doubt you have any STD, and certainly your risks for STD have been low, given oral sex as the only unprotected exposure recently. Your problem is quite similar to the one in the question immediately before yours, with the exception of your biking history. Certainly that can cause minor trauma to the prostate gland, as well as to the pelvic musculature. Take a look at the other thread, as well as the ones whose links I provide in that response:
http://www.medhelp.org/posts/STDs/Odd-happenings---Confused-/show/1918472
Given the likely contribution of pelvic trauma from biking, I suggest you sit tight for a week or so; your symptoms probably will clear up. If not, it would be reasonable to be examined professionally. That should include testing for common STDs, but I'm confident nothing will show up.
I hope these comments are helpful. Best wishes-- HHH, MD