Tinkerbell is right, Vagifem is best if you think the estriol cream might be causing irritation. I use Vagifem nightly (not just twice a week) and am also supposed to use an estriol cream externally every other night but can't get on with either Ovestin or the generic 0.01% estriol. As well as using just water to wash the area, and going knickerless whenever possible, you might also try a vaginal moisturiser, either Sylk or one of the Yes products. These are the brands least likely to cause further irritation, although we are all different, and it is as you say, trial and error. Another thing you could try is Multigyn Actigel, which helps to balance the vaginal flora and prevent or treat bacterial vaginosis. I did find that when I was using an estriol cream internally, this could be a problem. Actigel stings on initial application, but it is effective if you think you might have BV, and the stinging does wear off. Good luck.