Couple of quick options.. Assuming this is in a sump.
Take the cup off and just let it run for a couple days, it will work itself out.
Do a water change, 10% will usually calm a skimmer down when it is doing what it is doing.
If you have a sump, just pop off the top let it run, it will start working shortly. You can look at the top of the foam and when you start to see some brown/yellowish then pop the skimmer cup back on. It may overflow a little bit more, but it will stop.