Hey thank you guys. He is up to date with worming and I just discovered today that my other miniature has it too but on his mane. I also started usuing betadine today incase it's a fungus but I don't think it's rain rot for some reason. Ironically, it has been raining for the last 2 days so I havnt been able to take photos but it seems that whatever this is, it makes sections on the baseline of the mane/tail swell up like balloons and make the horses itch them untill the skin is raw.
I'll see how it goes until tomorrow and then I'll put some photos up. If it doesn't get better I'll definitely try some medicated shampoo or call the vet out.