well there are a bunch of clinics in san francisco (i used to live there), including one on haight and ashbury...and a bunch of others. i threw out the larkin street business card thing that had all the numbers for the clinics though, but a basic clinic will set you up with some kind of way to get your meds or at least tell you how. oh wait, here are some free to no cost clinics, that are all in SFC proper.
they could at least explain to you how to get low or no cost medications. there is a list of many different insurance programs that you could qualify for, including cobra, medical, healthy families, etc. if i were you i'd call, say you had a psychiatric evaluation but no way to get the meds anymore. make sure they know you've already been on the medication, because they'll see that as more urgent.
the people at these places can be quite snippy and vague but eventually you'll reach a human being who can at least give you a decent referral! good luck
St. Anthony Free Medical Clinic 121 Golden Gate Avenue 241-8320
Haight-Ashbury Free Medical Clinic 558 Clayton Street (at Haight) 487-5632 (i'm guessing 414 area code?)
Potrero Hill Health Center 1050 Wisconsin Street(at 23rd) 648-3022
Mission Neighborhood Health Center 240 Shotwell Street (at 16th) 552-3870
General Medical Center at SFGH 1001 Potrero Avenue Hospital Outpatient, 1st Floor 206-8492
South of Market Health Center 551 Minna Street (between Mission and Natoma, 6th and 7th Street) 626-2951
Chinatown Public Health Center 1490 Mason Street (at Broadway) 705-8500
Silver Avenue Family Health Center 1525 Silver Avenue (at San Bruno) 715-0300
San Francisco Free Clinic 4900 California Street (at 11th Avenue) 750-9894