So this is my first brew, everything was going great within 3 or so hours foams began to appear, krausen formed, and there were bubbles constantly coming out of the airlock. This morning I woke up and went to check the brew, more foam than yesterday and a little more krausen. I just got home and all the foam is gone, bubbles are still coming out, and there are these brown/orange spots on the surface around ~1cm in size. My rubber stopper seems to be a wee bit small and got pushed down but is still holding at the top when I opened it to smell the batch. The batch is starting to smell like beer. But mainly I am concerned about the no foam all of a sudden in less than 12 hours and these spots.
The loss of krausen is a perfectly normal part of the brewing process.
Usually you get a load of krausen and bubbles and other fun for the first 2 - 5 days of fermentation depending on the original gravity of the beer, the style, the yeast and a few other factors.
Fermentation will then slow down; Less or no bubbles coming through the airlock, the krausen subsides, and sometimes you will get the little circles of foam or bubbles (though I'd be keen to see a picture if you can, just to be sure!)
Some brewers (myself included) choose to rack off the sediment at this point (literally transfer the brew to another fermenting vessel using a tube) though others will recommend not doing this; It's a personal choice!
Check the gravity using a hydrometer; If it's close to what you expect final gravity to be then it's probably just fermented itself out. Check it again for 2 more days, and if it doesn't change then you're good to bottle/keg!
The most worrying things are the formation of a 'pellicle' which is a thin skin on top of the beer, off/sour smells and an unpleasant/sour taste when you sample the beer, which would indicate an infection of some sort... Otherwise it's probably OK!