Kitten not eating

A few weeks ago we adopted two kittens. They were treated for Concordia, and overall have been playful and healthy. They are sisters and one is larger than the other, but the smaller one is a bundle of mischief and energy. We are feeding them grain free dry kitten food out down all the time and wet high protein kitten food wet three times a day. Usually the smaller ones squeaks like crazy when it is mealtime, but after breakfast yesterday she quit doing this. She doesn't seem to be eating as much as her sister and walks away when I try to coax her to eat wet or dry food. She's still doing this on the evening of the second day. She maybe eating some when we are not looking but she usually eats right when I put the dish down. Her sister was finicky too for about a day, but we gave her another flavor and she ate. The smaller one scarfed down a few treats this morning, but does not seem to be eating much. She just stares up at me when I try to coax her to eat. She still seems playful and healthy. Any advice? I called vet tech today and they didn't seemed concerned. She did gobble down a different flavor this evening.

Sorry meant treated for Concordia.

C_o-c-c-I-d-I-a autocorrect

Is she using the litter box normally and drinking water? 

Yes, she is doing those just fine. Since then she has started eating again, at least today, and seems to have some energy back. Is it normal for a kitten to refuse food for a day or two just because they don't like the food they're given. We have tried a lot of high quality foods on her. 

Yes, it's very common for kitties to refuse food if it doesn't appeal to them.  I would suggest finding something she likes and sticking with that.  My favorites for young kittens is the Royal Canin babycat dry and canned options.  They've always worked well with my littles.

Thank you.