I Have A Lump In My Abdomen, Swollen Lymph Nodes

I have a lump in my abdomen, swollen lymph nodes throughout my body, including under left armpit and above collar bone, accompanies with black stools (on & off), pain that feels like menstrual cramps, although I've had a complete hysterectomy. The pain radiates to my back and goes up my spine. Very fatigued and short of breath all the time. I cannot do any activity. Been going to my GP for 2 years and he tells me it's just lady middle aged stuff and the swollen nodes arent' big enough to worry about.