I've been having a hard time in pooping. This happend around 4 days ago. I ate dinner outside and the next day i couldn't poop at all. it was very difficult.the day after that i was able to use the toilet. i had to use toilet often the first few days. since then it has been happening to me. even before I was told to maintain a diet because a similar thing happend (black poop came at the time). now im curious why this is happening and what should I do about it?