My midwife recommended fybogel. I think you can buy it from most supermarkets. You have to drink it pretty quick after making it though as it starts ti get very thick very quickly.
Pregnacare made me so poorly I’m now taking the boots own brand of pregnancy vitamins (not sure if this may be what your taking ) x
I got prescribed fybogel because I've been having a terrible time and it's definitely helped. Also eating dried prunes (not the most delicious but you only need a handful). Magnesium citrate supplements also have a laxative effect and I think they're safe in pregnancy (best to double check) but I struggled with the size of the capsule and couldn't swallow them.
Are you taking pregnacare? That supplement was terrible for me… I changed to just taking folic acid pills and the constipation got better. Also I’ve found eating meat is somehow helping - I’m eating lots of beef and turkey mince. Also being as hydrated as possible helps a bit. I’ve had a bad couple of days though so I feel your pain!