My stomach gets upset everytime I think of something stressful, worrying, answering exams, whenever i'm late at school, or sometimes just plain waiting and also when i feel uncomfortable about something. It feels like i need to go to the bathroom even when i already did or doesnt need to. I have observed this from myself from my early teens up to now im 21y/o male and i think its affecting me more than before, especially my concentration on much more important things like when listening on discussions, focusing on presentations or in answering exams calmly.