Sore on mouth and tongue

[katiehorse]

There are no buttercups or clover in paddocks. I found a sore on my ponies lip only small. The next day it was double the size. I've been putting sudo cream on it. Today I checked and i noticed a similar looking sore but on side of his tongue. Any ideas? Could it be from bot fly?

 

[lamlyn2012]

Do you have any common hogweed in your grazing?( Also known as cow parsnip.)

 

[katiehorse]

I haven't noticed any. I'll have a look later tho