I Have A Tennis Ball Sized Lump Deep In My

I have a tennis ball sized lump deep in my but cheek it bothers me to sit just after minutes of sitting it seems my legs get tingly so I have to sit mostly on the other butt cheek. You can move it around and seem to poke out more if you message it. I think it's also causing sharp pains in the pelvic area and around my sphincter. More like horrible pressure around my sphincter but sometimes sharp pains too. I have never felt this kind of pain only while giving birth but now that it's starting to happen more frequently everyday it's starting to scare me. I don't think the docs are that great here in bonners ferry idaho since they have over looked it once already now I have to go back there again....