Hi HandyAndy,
Yeah I know how it is to be 15 and to embarrased to discuss personal problems with your parents. Other than your semen being yellow are there any other problems...smelly, burning, pain? If not go to the drug store and buy some cranberry pills (you can get these over the counter), take as directed on the bottle until they are all gone. Drink plenty of fluid, water, gator...no sodas or carb drinks. If your semen is still yellow go to the "parents" and tell them you'd like to air on the side of caution and see a urologist...they will understand...they too were your age and dealt with parents.
Good Luck, and please keep us informed.
Faded Rose
Oh, if you are having pain and it is smelly you probably have an infection and need antibotic...you will have to go to a doctor for that.