What Causes Constipation And Stabbing Pain From Navel To Vagina?

83 yr old female, history of ulcerative colitis (well managed w mess), breast cancer - lumpectomy/radiation 5 yrs ago, recent weight loss in last year (89 to 80 lbs), recent symptoms: hernia, occasional constipation, stabbing pains from belly button into vagina, leaking bowel - slow leak and cannot tell when will happen, family Dr felt small lump in rectum.