How do I get my mare's main to grow back without any expensive gear?

My chestnut mare Lucky has a case of QLD itch, I've been trying to work out how to get rid of it and get her beautiful mane back like it was. But I can't seem to work it out. Can anyone help me? Please?

MTG. You can get it at tractor supply or just about any feed store. It smells like bacon grease and it's kind of yucky but it really does the job.

I'm not familiar with what causes Queensland itch. Is it fungal? Parasitic? Have you consulted with a vet? I would think asking some fellow Aussies would help, and we have quite a few here.

Come on Downunder folks.....help out here.