Your difficulties may have to do with what type of parasites you have. Ascaris are the biggest menace and tend to block the intestines and rob moisture, causing constipation. Some times when asascaris feel threatened they will bunch up or ball up. As a temporary measure to not get yourself in too much trouble with blockage, you could try the magnesium citrate that is purchased at any drug store or grocery store.
Later, you might want to try senna or cascara sagrada herbal formula for constipation.