What Causes Constipation With Bouts Of Diarrhea And Abdominal Cramping?

Hi ~ I am a 32 year old female. I lead a healthy lifestyle with exercise and healthy eating. I ve struggled with constipation my whole life, but it usually comes and goes. After my first two pregnancies it seemed to get better, now after my 3rd child in December 2014 everything seems to be haywire again. In March of last year (3 months after my 3rd chid was born) I had what seemed to be a gallbladder attack. I had some testing done that showed sluggishness in my gallbladder, but instead of surgery I fixed it through dietary changes. The last 6 months or so I ve noticed a worsening of many things - constipation with bouts of diarrhea, ocassionally severe abdominal cramping, bloating, feelings of fullness, pressure in my vaginal and rectum areas that comes and goes, fatigue. My menstrual cycle returned in August (8 months after birth of baby) and it has been very painful each month - pressure in the vaginal area, heavier bleeding than normal. 2 weeks ago I began having a nagging lower back pain that is still present. Now this week I had what seemed to be a stomach virus with severe abdominal cramping, and diarrhea for 24 hours. 2 days after that ended (this week Wednesday) I had a very odd stool with a lot of noticeable mucus. I am very concerned based on what I am reading online as to what it might be.