Hey Daisy – welcome to the BSD forum. I’m a little puzzled by the pain and discomfort, the only thing that occurs to me, is maybe you have upped your fibre intake and your body is adjusting to that, but normally, people haven’t been reporting pain. Are you making sure to keep well hydrated? This is important as it helps to keep everything well lubricated and able to work smoothly. It seems the problem is settling down now, but if it persists, it may be advisable to get it checked out with your doctor, just in case.
Hope you continue to see really good results. Expect the rapid loss to slow and even plateau at some point, but stick with the programme and it will all come right.
Good luck …