Longer post, but concerned.

So, earlier on in my pregnancy I had a staph infection below my knee that is now treated. Now I have another, what started as a pimple, under my butt cheeck. It's extremely painful to sit down or walk, and when I squeezed it earlier I was able to get some green gross stuff out. Now, it's way too sore to squeeze and it very hard to the touch! If anyone knows what this could be, please help me. I am very nervous, and nothing now is coming out when I squeeze, it's just hard to the touch and extremely sore.