What's a good way to control urethritis until i can go to a doctor?

Cranberry juice or: Vitamin c tablets (not oj) to acidify the urine. Plain cranberry juice (not the "cocktail") acidifies the urine as well as helps prevent bacteria from attaching to cells to infect them. Plenty of fluids to flush the system; urinate when first get urge, don't postpone voiding as that can stretch bladder, weaken it so that some urine remains, which easily gets infected.

See a physician ASAP: You need to rule out an std (venereal disease) which would be a common cause of urethritis in your age group. Once an std has been ruled out, a simple course of antibiotic therapy should be curative.