Your doctor tried and failed. He isn't treating the whole problem. Firstly, you don't necessarily need antibiotics to rid yourself of this and I'll get more into that in a minute.
Second, eating yogurt isn't going to do it unless it's organic yogurt and even then you probably aren't getting enough of the beneficial flora. Go to the health food store and get a probiotic supplement--Ultimate Flora is an excellant one. It works for me. There are different potentcies you can buy, I go with the 15 billion. When I am ill, I take two a day instead of just one until I am in the clear. Then continue to take one a day for a couple weeks.
Thirdly, have your significant other get tested to make sure he hasn't contracted it from you. He can be carrying it w/o symptoms and just giving it back to you over and over again. He may need treatment.
About the treatment for you. There are a few different vaginal infections you could have and depending on which it is you have to treat it differently. I used a wonderful book when I was in a similar situation and it helped me identify which infection I had and how to treat it. Now that I know I am prone to it (it starts up when I've been eating a lot of sugary foods) I can treat it effectively and it never fails.
The book is called The Complete Book of Essential Oils and Aromatherapy by Valerie Ann Worwood. I know the title doesn't sound like it would be helpful but with a combination of spring water, apple cider vinegar, lemon juice and lavendar and tea tree oils I was able to restore the acid/alkaline balance down there and rid myself of the infection and start feeling relief right away. I shared it with my mother and she swears by it, too. We never have to go on antibiotics for that stuff anymore. It was Vaginalis Gardnerella that was plaguing me which is actually an infection of the vaginal secretion. Basically, the vagina becomes too alkaline making it very itchy. There are a few other similar infections listed along with their treatments. You can buy the book or I can scan and email the particular pages to you if you are in immediate need. Email and let me know if you'd like this further info.