Is it okay to try giving my baby her formula cold to help with thrush?

My 4 week old daughter was diagnosed with thrush yesterday, it is only on her tongue and she's been on Nystatin (sp?) for it since yesterday which has been helping a little bit - she's now eating like normal and she's been a little trooper, but I feel so bad for her and can tell it's still bothering her : ( - I just let her suck on an ice cold waschloth which seemed to help some but someone on another site just suggested that giving her her bottle cold might help as well? Not refrigerator cold, but just room temperature. I am tempted to try it (if she'll take it cold) but want to make sure it's safe first? I'm a little nervous about it, I don't want to upset her tummy or risk making her sick. Just want to do anything I can to soothe the pain/itching on her little tongue! Thanks!