Stomach discomfort. Day. please advice.

I have been facing slight pain in the left side of the stomach.beside the Belly button..it's a slight flank pain that comes and goes off. Too much gases and bad smell farting and sudden evacuation. Sometimes suddenly I get stomach pain and need to empty out within no time. There is no normal bowel movements. Sometimes constipation or another time bad smell poop. And always having a feel like to poop. Discomfort feeling and scared to eat anything as I might suddenly get a stomach pain and need to poop. Even if I have to poop it's always incomplete evacuation. Even though the stools are not hard it is still incomplete. A little is left at the opening for which I have to use gloves and with the finger circular movements I need to clean out. Which takes me a lot of time. I am not on any medication but I have stress and have very low appetite and irregular sleeping and eating patterns. I sleep around 3am and start my day at 2pm . My water intake is also 1 litre a day. Please Advice.