If you do not have insurance, next time this occurs, get a sample in a bottle and get into your local ER, be sure to tell the admitting staff your son is in pain. This is a one-time shot, you won't get much attention if you try again.
Clinic docs are most often overworked and can overlook or misdiagnose even serious conditions if they don't present textbook or are in almost anyway occult (thats as in 'hidden').
A careful and sympathetic ER crew might (that's as in 'maybe') be able to call it.
Does he have pain in his side/lower back?
I just had those symptoms and it was a kidney stone, but towards the end the pain was pretty intense.
Don't know about "clots," but on and off over the past 20 plus years urine tests have found blood. After one of the early findings doc sent me to the urologist for a "shove the little cam up the urethra" to check bladder for tumors and things. Nothing was found, blood continued to show now and then in testing but its now been about 6-8 years with no blood showing so who knows. Guess it fixed itself.
"Chop it off."
- Inuyasha Girl 93
congrats, you're son started his period haha I'm a girl so I can't give you advice but I'd take him to a doctor if I were you because I don't think that's normal unless you're a chick