Help with sudden facial hair loss

[wakijaki]

I've got an 18 year old cob cross gelding who has lived out since I bought him.
He's in with 2 friends horses and we rota the daily checks so I've not been up there for 2 days due to work. However checked him today and he's developed bald patches on his face..mostly down the center and some around his eyes.
Any advice

 

[wakijaki]

Having trouble uploading the photos

 

[Elf On A Shelf]

Probably a bit of rain scald.

 

[Red-1]

Or he was hungry and the grass was greener at the other side of the fence/ tree?

 

[Gloi]

Looks like rain scald. If he's never had it before a Cushing's test is a good idea.