Your coin is, if it is true, a smaller variant of the "usual" Apollo
rider coins from Kolophon. Usually they weigh between four an five gram, this variant only between two and three.
Your coin is a bit
corroded, so it cannot clearly be seen whether there is a spear or not. But the position of the rider's arm
is exactly the one for holding a spear.
When searching in Isegrim
for coins with a head
and a magistrate's name ΙΚΕΣΙΟΣ, the only ones with a horse
on the reverse
are from Kolophon.
I don't have alternatives, but it's up to you to continue the search