Ringworm itch help

DD had two little spots of ringworm on her arm - probably got it from one of our cats. She couldn't even sleep Thursday night. She put on hydrocortisone, benadryl, etc. The next day, she and her father went to a cattle show and a rancher told her to put fingernail polish on it. She said it worked wonderfully. And today the spots are almost dried over and gone. I wonder if this wouldn't work for mosquito bites.