Before you rush off to give Adobe your money for a year, give this a try. Krita You'll need to adjust a few things for pixel art and a more photo editor like experience. Here's a video that explains how to do that. I was looking at this until someone who has a prepaid creative suite made me their +1.
Addendum: I just checked my youtube feed, and one of my favorite tech channels has just posted a video about Krita. The person doing the video is a professional graphics designer, so she really knows more about this sort of thing than I do. Please take her opinion on the matter before you take mine.