i think the high-dose nitazoxanide killed off a lot of your good bacteria. i had similar experience 8-9 years ago when i took a 3 week course of tetracycline pills. at the end of those 3 weeks food was passing thru me totally undigested - carrot particles bright orange, pieces of lettuce looked as fresh and green and crisp as they did before i ate them.
i didnt have health problems before the tetracycline but i began to soon after. my teeth started falling apart, have had 5 root canals since.