I learned the hard way about p&b shakes. I think they're way too hard on the body for a lot of people, think glue + cement + delicate mucus membrane. My problems started with a history of constipation, followed by P&B shakes-> blockage -> urinary infection -> kidney infection within a day -> Antibiotics :*(
if the advice from Hopsino doesnt improve things within a day, go to the Dr and get something for your kidneys, don't mess around with kidney infetions. Then you can go out and get a lot of acidophilus and bifidus (which you don't mention having taken), get yourself back on track, and start again, carefully.