Swollen Lump on Bridge of Nose

[mongy46]

My horse has just had a lump come up on the side by the bridge of his nose.

It's a soft lump and seems to be getting bigger.

He has been stabled for the last 4 days.

Does anyone know what it could be? and how to treat it? ie Arnica gel?

 

[hunting mad]

Could it be a problem with his synisis(sp)