Give it plenty of time to ferment out (5-10 days). Anything that's not an infection will fall with the krausen. Anything that is an infection will still be colonizing on the top of the beer.
It is REALLY hard to infect a beer with bacteria. You have to pretty much hand deliver bacteria into the beer straight from your own hand to infect a beer. Even then, most bacteria can't survive in the alcohol and CO2 environment. So 9 times out of 10, it is just a weird krausen. Give it some time and it'll probably fall out of the solution.