Hello I'm 31yr Old Female. I've Had A Gastric Bypas

Hello I'm 31yr old female. I've had a gastric bypas in 2009 and since then I've lost 300 lbs but I ha e constant pain. I'm on strong meds and no releif. Finally got ct and my colon seems slow. I've started only having bowel movements af night n its diarea almost like a big gush of force. Also had hidascan yesterday and the test showed no rradiation stuff even able get to gullbladder. Tesg was stopped bc was not even possible to go to the gullbladder. Met surgery today n go for removel of gb thursday. I had a spell today where I was reportex to become pail confused and clammy. I sweeg so bad had change close. Also caused a major migrain. I'm hoghly scared and confused. What causes this stuff?