I Have IBS And Have Had Issues With Constipation For

I have IBS and have had issues with constipation for the entire month of January. I've been checked by my schools doctor and had a full round of bloodwork. Bloodwork says im healthy as can be and the Dr suggested just to increase fiber and take Metamucil. ive done so for 5 days. Starting yesterday ive had extremely painful bowel movements, sharp pains that last for 20 min or more. the poo is a a marble color of tan and dark brown with bits of tar like stool. In between bowel movements im in a fair amount of discomfort, itchy anus with a pressure like feeling that causes moderate to sever pain. 2x Advil 200mg does not seem to be helping at all.