Allergic reactions to psyllium can involve chest congestion and sneezing.
Try switching to flax seed fiber and apples instead for awhile and see if the symptoms abate. You can also get a good whole grain cereal mix that will give you plenty of fiber for cleansing AND good diet purposes, and then just drink the Bentonite clay several times a day.
I like "Bob's Red Mill" cereals, available at most health food stores. Some of them are even minus wheat, which some people are sensitive to.
Many people in manufacturing and health care are sensitive to psyllium because of how it's used in packaging.