Couple things to consider....
1. How quickly did you up your calories and by how much. I know what the math says about 500 cals above maintenance...blah blah. But honestly....you up it 500 calories, your body adjusts, you up it more, repeat. By the time you are done, you may be 2000K above where you started. And depending on your level of development, coming off a show diet, etc....that delta could be MUCH greater. To simply go from 2500 to 5000 cals will of course cause fat gain....FAST. You have to work up to those levels in increments.
2. Where are your carb levels, and when are they ingested? Keep them to PWO mainly, or lower them if you already do this.