Thank you for your answers.
Numiswiki was the first place I looked in. Judging after the distribution of the letters on the
obverse I am 99% sure it is
Constantius II As for the
exergue - that is hard to read. Arminius distinguished N Γ but I tried looking at it until my eyes started to hurt and I can not say anything for sure.
I will take better photos in a few hours and edit this post.
Later edit: this is the maximum due to light here in the office and not the best camera.
Size of the coin - 13 mm (if this has any relevance)