ABOUT MY DOG

Okay, before I get yelled at, I know this isn't the place to post. However, I haven't found any dog forums!!! I need help. My 1 year old lab has terrible dandruff, and these red spots that look like bites. We've been to the vet and they guessed ants but it isn't so now they "don't know". I took a pic of the dandruff spot and it is yellow and there's a black spot when you zoom in. She is on flea medicine, and is an inside dog. We have 2 cats and neither of them have any signs. Please help since the vet is baffled!!