I agree with CurfewX. Tell your doctor and I am almost positive they will tell you that everything will be fine. Sometimes constipation happens during pregnancy. Is this why you were taking it? There are natural ways to combat that. When is your next doctors visit? How far are you now?
Most supplements will state that they are not recommended for use during pregnancy, but that doesn't automatically mean they're dangerous. Since supplements aren't regulated or tested by (in the US) the Food and Drug Administration, they can't claim that they're safe during pregnancy - again, this doesn't mean they are UNsafe.
This article has a lot of good and credible information: https://www.livestrong.com/article/460259-safe-fiber-supplements-during-pregnancy/ So, you should check the ingredients in that supplement and see if they are generally considered safe.
Most of all, it's important to let your doctor know about any meds or supplements you were taking right before you got pregnant, or while you were pregnant.