Cymbalta and lower abdominal pain

I am a 3 time Ovarian Cancer survivor, have had 4 abdominal surgeries, adhesions and have developed Chemo induced Peripheral Neuropathy in my whole body. I've been taking Cymbalta for about 18 months. I've been having lower abdominal cramping in my ureter and bladder area the last 2 months. MRI and PET scan are negative. Could Cymbalta be the cause? I can only take 20mg because it causes such severe constipation. I take 800mg of Magnesium Oxide every morning and 1000mg of Methylcellulose at night, vegetarian diet, no flour products, exercise every day. Could the Cymbalta be causing the abdominal cramping?