This is a very local fiesta, located here. It is a typical Galician fiesta... for a weekend, one small village (maybe 20-30 inhabitants) is flooded with people (2000-3000) for a weekend. Tents with food, a small marked and locals riding their horses to get there (horse = no parking problems... we had a 15 minute walk from where we parked).
Now I am not an expert on these "Santos", but as far as I understand today is "San Fermiño", so this fiesta is surly celebrated all-over Spain. If San Fermiño and San Fermin is the same thing, I am not sure, but I do not think so... since San Fermin is not celebrated in November.
Today is Martinmas, the feast of Martin of Tours, patron saint of innkeepers and reformed drunkards among other things. Traditionally the beginning of winter, and based on the Roman Bacchanalia and always a time for revels. If I look for example at http://www.paxinasgalegas.es/festas/ I see plenty of San Martinos but don't see Fermino anywhere - perhaps that is local to that village, perhaps the church is dedicated to Fermin for some reason.
ah, but it probably isn't "Spanish" but Galician, in which case it would be the normal ending, as in camino/camiño. And if it's the same Fermin, he was born in Pamplona - although of course it might well be a different person entirely . . .