I've never found any over the counter treatment to work - the only thing that worked for me was some antibiotics from the dr.
Make an appointment asap and then if you cure it yourself before the appointment you can always cancel it
Best to go to doctors any doctor will tell you that these sachet things just sooth the pain they dont sort it. Doc will put you on antibiotics to clear it up. For future drink cranberry juice its supposed to stop any bacteria sticking to the urinary tubes. Even if it seems to have gone go see doc he will do urine test