When I breastfed I was treated extensively for thrush. Thrush is basically a yeast infection in your breast. The common treatment is an oral treatment of fuconazole (an anti-fungal pill)--it is safe to take while breastfeeding.
I was also treated with a topical home-mixed treatment of miconazole cream (the cream you use for a regular yeast infection--known as Monistat--that's one brand name), triple anti-biotic gel (Neosporin is a common brand name) and a pain relief medicine (I can't remember the name). The exact "recipe" for these was given to me by my lactation consultant who is La Leche League certified. These are all over-the-counter creams and it isn't that expensive to use them but if they work, it takes a lot longer to be cured. Also, before you pump milk you need to remove the cream with mineral oil which can be inconvenient and irritating to your skin if your nipples are sensitive.
There is also a multi-purpose cream that is specially mixed for you a the pharmacy that I'm sure Sarah can give you the name for. The reason why I made this one of my last-resort options was that it cost nearly $200 USD for only a few ounces--it was SUPER expensive where I was at. I did end up buying this but the steroid in it made the condition worse. It is a mixture of three things--including a steroid. It is safe to use with breastfeeding and does not need to be cleaned off before you pump or nurse.
Lastly you can take a messy but cheap route and use Gentian Violet. This is a dye that comes in a bottle that is similar to topical iodine. Iodine dyes your skin a yellowish-brown color and Gentian Violet dyes your skin purple--it stains it purple. This is a really old remedy for thrush and Gentian Violet is dirt-cheap (I think you can pick up a bottle that will suit your needs for less than 10 HKD--and if you can't find it in HK, I have an unopened bottle from the US that I will give you for free). If you do the Gentian Violet route--just know that it's messy and will turn the milk kind of a blueish color but you only have to do the treatment for 7-10 days.
One thing to look for with thrush--is the inside of your baby's mouth covered with a whitish coating--that can be a tell-tale sign.
Hope you get things worked out.
Also, to help support your body, it's a good idea to stop eating all sugar because yeast infections feed upon sugar--so cut out the candy and sugary foods while you're being treated. And, it's a good idea to take a probiotic to strengthen your immune system--these recommendations helped me a lot.
