Hi I have another idea about this coin.
It seems to me like some little coin from messalia(marseille or marsiglia)cisalpine gaul,struck in the 1 st century b.C.with athena's helmeted head on the obverse and a caduceus on the reverse,these coin are very thick and little as diameter.
On the reverse of your coin the caduceus is very visible(like two rings together).
unfortunally now I'm not able to find on the net the example similar to your coin I've seen sevreal time ago...maybe later I'll search again.