I have a lump in my right buttock cheek near where it joins the top of my thigh. Came on quickly. There is some pain. Frpm sitting, and squeezing, it has sort of flattened out. Seems larger in morning, smaller at night after applying hot compress. I have ankylosing spondylitis, which means one of the side effects is occasional swollen glands. This happened to me a couple months ago, then went away. Good home treatment ideas?