I Have What Appears To Be A Knot/lump In My

I have what appears to be a knot/lump in my lower abdomen that moves depending on my positions, if lying, standing etc, it does not hurt but it makes my stomach look distended. (I look 3 months pregnant) I am not pregnant, but I have always have horrible periods, terrible cramping, back pains and clotting. I've also noticed I've been really gassing as well, at first I thought the distended stomach was because of that but once I felt the lump/knot I'm not too sure