What is making my pony so itchy? Winter coat, flies etc ?

My pony is losing his winter coat still as he is a very fluffy native and so is a little itchy all over from this, however over the past couple of weeks he has begun to itch his face lots. At first i thought it was just him losing his winter coat but he has continued to itch his face and now has lots of bald patches on it and is rubbing it raw in places! it seems to be getting steadily worse and worse and he is itching on the water trough and making his face bleed ! its not sweet itch as his mane and tail are fine and i've tried anti itching creams and just hibiscrubbing the area, any suggestions on what it could be ?