The first few weeks with a j-pouch are 'difficult' to say the least. I wasn't prepared for how it would behave after surgery at all. It definitely isn't like a healthy colon in the beginning.
That said, you begin to try and thicken things up by using psyllium husks, eating soluble fiber foods - like oatmeal, and thickening foods in general - like peanut butter, cheese, potatoes. As Winterberry said, go easy on the sugar. I can cause pouchitis. I'd also suggest you try Imodium tablets to help slow things down. You can take up to 8 a day.
If things continue to 'flow' without slowing down, I'd contact my GI or surgeon and get checked out. You might have a case of pouchitis that can be treated with antibiotics.
Hang in there! With time your j pouch will begin to adjust and life will get back to a 'normal'.