I recently bought a whey isolate which is 100 %whey isolate only(nutrabay series whey isolate) .i consume it only once a day after my workout and have noticed that my bowels are very frequent .i have the urge to go take a dump very frequently and my bowel is pretty loose as well as dark brownish.also throughout the day i feel as if theres a lack of energy and a mild headache in the center of the forehead .is it normal while taking protein shakes?