I've never put Monistat on my nipples, but I've put Lotrimin. (as well as Grapefruit Seed Extract, Gentian Violet, Diaper Rash Relief Ointment)
I also take probiotics as well as feed my LO some by dipping a wet finger and feeding it to him. You can also break open a capsule and depending on your baby's weight put some in his breastmilk. I believe at 3.5 months my pediatrician said one capsule a day spread over maybe 2 feedings.
Find a quality probiotic/acidopholis (usually located in the refrigerator section of a health store)