im 17 male and this started 2 weeks ago , but i had sexual encounter a month or two ago (in case theres an std that does that...or could this be a tummy infection? i dont know ...but only 2 weeks ago every single day it started to smell very bad from a distance...i have to shower every day and still have that smell right after i urinate and the smell is stuck in my underwear..its like i have to shower twice a day to keep that from happening but my question is what in the world could cause this to happen!

anyone have any advice?
ill take what ever you guys could give me..