My friend is in agony with cystitis... she need some advise!?

My friend has cystitis and has been to the doctor and got antibiotics, she missed 1 day but apart from that she is on track with taking them... she has just called me up and she said she is in agony still and has been drinking water and no alchol like advised... i have never had it so i don't know how bad it actually is but she is not a wimp or a hypochondriac, in fact its out of character for her to complain so much! she doesn't need to go to the hospital but does need some advice if anyone can help, a quick remedy or pain reliever is what i'm hoping for, anything at all that may help her? !