Void anything being wrong with hardware, something must have gotten in your water to make the skimmer go nuts. Lot's of reasons skimmers act up. I have had a few Reef Octo's do this to me after the skimmer was broken in. Usually, these issues subside after a few hours. You said it was getting thicker up top? If you let the skim line drain into a bucket, does the water accumulate fast?? It can look like a lot coming over the cup, but if you really measure in the bucket, it's usually not that much.
Other questions, is the height of the water line on skimmer correct? Usually the manufactured states a set line where it needs to be. Has that changed? Did your auto top off change in any way??? That would also throw skimmer off....