Hi UK lady,
I suffer from the same problem and I'm in week 10! I have been using laxose as this is the only thing that ever works for me. I know it probably takes me out of ketosis but the relief is worth it, I have also maintained a steady weight loss. I mentioned it to the pharmacist yesterday and she recommended dulcolax tablets. I tried just 1 last night and oh dear god, all I can say is the pain I experienced from 3am was worse than labour and my labours were pretty bad! NEVER AGAIN am I taking one of them. I didn't even go to the loo yet. I felt so bad I thought I was going to be sick also. My tummy is in bits today, only had my first shake a few minutes ago and that has set the pain off again. Theres my ramble over, anyway you are not alone!
Laxose is way more gentle and I will be sticking with that in future as fibre clear does nothing for me either.
Good luck!