What Causes Lump In Buttocks?

I have a lump in my butt like under the skin on my right cheek . It s tender when I push in . I don t think its hard but I can t really push around too much because it s tender . I have had a lump removed from my leg before same leg like same side as the butt lump and it was just fatty Tumor or whatever . This one feel more soft than the one I had removed .