I am so sorry! I am sure that is so scary and overwhelming! I would first get my trainer to take a look, and if he/she doesn’t figure it out, I would have a vet come take a look. This happened once to my mare, but It was her whole body. I just let it run it’s course and she just shredded out really nicely. When we had the vet/chirp out for other things I did ask him and he said not to worry, some horses shed more than others. But it is a little late for shedding, and it is odd for just one spot. I would definitely have other people take a look and give you their opinions. Sorry I couldn’t be of more help!
I was brushing her legs the other day and I noticed that a lot of hair was coming off of her legs, I assumed it was just shedding. Then today I was brushing her again and she was still “shedding” a lot. I pulled a little bit out with just my hands and a huge chunk came out. I did it a few more times and it just keeps coming out! I put a cream on the spot where hair was coming out but as I was putting it on more was coming out. I’m really worried! What is it and should it be treated with medicine?