Feel A Stitch Like Feeling Under Left Rib And Breast.

Feel a stitch like feeling under left rib and breast. Even though I have had bowel movements, still feel constipated. Had a mucous stool with blood and called my doctor last wednesday. He started me on an antibiotic and told me to take a full tablespoon of metamucil in 10oz water and follow that with another 8 oz water daily. I've been doing all that was prescribed although, Ive been splitting the metamucil to 1 teaspoon in am and one pm because it is difficult to take all of it at once. My stool is maybe 10-12 tiny hard pellets each time. There is no longer mucous or blood, however, the full feeling is consistent. I still feel as though I have not had a cleansing bowel movement. In addition, whenever I eat, I feel very full.
My question is: Is it common to take several days for the metamucil to actually help empty the bowel. I feel like I'm putting a lot in and not much is coming out.
I should also tell you I am drinking about 60 ounces of water as well as hot tea and coffee.