It's happening all over. I've got a few doing the same. Didn't look fungal to me but had the vet take a peek anyway while she was in the area, she's seeing a lot of it this year. She said with the above average winter and early, quick spring they are losing winter coats without having a base grown in underneath first. Also asked my farrier when he was here Thurs, he said every place he has been has at least one doing the same thing.
Life is like a camera. Focus on what's important, Capture the good times, Develop from the negatives and if things don't work out, Take another shot.