What could be causing my dog’s sudden hair loss?

I have a 5 year old australian border collie. When I was brushing her I noticed she has 3 bald spots that aren’t really all that bad or noticable, but they still concern me. The largest is on her back about the diameter of a can of soda and already has spiky new hair growing back in. The second is on the outside of her leg and she has a completely bald patch the size of a penny that is slightly red. the last and worst is on the inside of her leg and is not completely bald, but is red and scaby and about half the size of a dollar bill. She has had dry skin problems in the past, but none since we started feeding her an all-natural organic dog food. She is not fixed, but has never gotton pregnant. She is lactating though, as she usually does for a while after being in heat. My mother says it’s just her winter coat comming in, but she always thinks eveything is fine when it’s not, so I dont trust her with my pets. What could be causing this?
we switched her food over a year ago. my mom also likes to feed her table scraps, even though I tell her how horrible it is for the dog. Could this also be the cause?

I think that you feeding her organtic dog food is really helping her. I wouldn’t worry about the bald spots anymore since they are slowly going away. If you are still concerned you should take her to a vet, but I’m pretty sure that nothing is wrong with her, if anything she could have been allergic to her old dog food.