Yeah my doctor said the same about using the powdered stuff. Metimusol type stuff...it doesn't taste bad, its just terrible texture. But if you put it in orange juice it dissolves better. Just down it and then chase it with a large glass of water. Make sure to drink lots of water or you'll make the constipation Way worse.
Good luck
Try taking benefiber that really helps me at times. I am 30 weeks 6 days and still suffer from constipation. .. but using benefiber helps me at times...
My friend dealt with constipation and her doctor told her that the powder fiber was fine. She didn't like the texture of it so the doc ended up prescribing her prenatals that had stool softener in them.