I really don't understand how shit works.

Yesterday evening I felt like I had to go to the bathroom, but all I had was two very small, thin, compact, and slightly-curved pieces of shit that lay at the bottom of the toilet, in the little depression where everything gets whisked away. Was that from all the coffee I had earlier that day, and if so, why wasn't the shit blacker? This morning I smelled my strong coffee brewing and I had to take a shit, and it was a little watery with yellowish pieces, and then like forty minutes later in the middle of my Hebrew lesson when I had finished the cup of coffee, I had to shit again, and it was large normal size pieces of shit, only less compact than usual and having the same shade of yellow as the previous shit, and it frayed a little bit at the edges during soaking. In less than eight hours, I had three very different types of shit. Honestly, what's up with that?