What could be wrong with me?

Now this is serious, if you going to say something disrespectful or make fun, you'll be reported. Ok, I've never really had problems with vowel movements but since two days (and a half) ago i hadnt had a movement. Just this afternoon i did and it was smaller than usual. Its been a month since i changed my diet in order to lose weight. This diet was given to me by a nutrionist, NOT A PERSONAL TRAINER. One of the things she added to my diet was whey protein... could this have anything to do with it? Or anything else? Thanks