as a veteran of repeated, vicious attacks of cystitis, can recommend the following measures:
if still early days you can help by flushing out with TONS of water. literally drink loads and loads of water and you might just shift it without need for any other treatment.
if you must drink anything welse, make it pure cranberry juice
NEVER drink anything else esp tea, coffee, alcohol or citrus juice until it is fully and completely gone - will flare it up and have you in agony as soon as it hits your bladder.
dont try to hold your we coz it hurts - keep drinking water and peeing even if it hurts.
you can get concentrated cranberry tablets from health food shops like holland and barrett. take a handful of those - even if its already quite sore this can cure it. again with the water though, always the water...
if nothing else works and you need to see the doc, dont let them give you general antibiotics, make them give you Nitrofuantoin (or Nitrofurantoin sp). take one after each sore wee, up the dose if its really bad and keep for the next attack.
good luck!