Ceoli, here are some thoughts:
Yeast overgrowth can be caused by pH imbalance, true but the underlying pH imbalance might need to be addressed, too. Are you eating well? Lots of different types of foods and of different colors? Avoiding alcohol? Sugar? (this seems to trip people up who have frequent yeast issues) Hydrated? Not too stressed?
Have you considered having your blood sugars tested? Sometimes an overgrowth of yeast can be secondary to chronic (if borderline) hypergylcemia, aka, diabetes.
Yeast is slow to grow and slow to die and will often require treatment lasting longer than the resolution of symptoms.
OTC remedies like monistat and lotrimin aren't working? Could it be Bacterial Vaginosis and not yeast? Nearly 1/3 of all women will wrestle with BV at some point in their adult lives. A simple culture can help you know exactly what you're dealing with.
Eliminate alcohol and sugar, reduce simple carbs to the best of your ability.
FemDophilus vaginal suppositories work well; eating yogurt helps replenish the good flora in your GI system but does little for the girl parts.
has a tincture kit called "Beat the Yeast" that some women swear by.
Reduce or eliminate vaginal irritants for 10 days or so...Nonoxynol 9, latex and glycerine based lubes can all be culprits.
Consider trying RepHresh, a Ph balancing vainal gel sold over the counter. It works 3 days at a time and for some women is a miracle, for others an irritant.
And of course, consider NO UNDIES, just like grandma used to do. No G string, no tights or pantyhose, either.
Good luck and feel free to ping me if you want more info.