Lower Left Abdomen Pain

Hey guys heres my problem, I'm a 15 year old teenager and I've been having this pain in my lower left abdomen for about a year now. I've read a lot about but gotten no feedback all I know of is that it's called diverticulitis. It's not so much painfull but annoying and uncomfertable. The longest session I've had of this pain was 8 or so hours. I've been to the hostpital 2 times had a x-Ray, cat scan, and ultrasound. And got nothing! Can someone help? The docotrs told me it may have something to do with my liquid track and it may be tangled or twisted which may be the cause and they also thouht it was a kidney stone but it wasn't. So I went to the urologist but still nothing! Help please!