not period related

This has nothing to do with periods, but hoping someone has advice for me😬 so for the past two weeks or so I have been so nauseous before and after eating and (sorry if this is TMI) but it seems like my food goes right through me and within 20 minutes of eating I'm on the toilet with diarrhea. I have no appetite and don't even wanna eat because of how crappy it makes me feel, but I force myself to eat because I know it's unhealthy not to. I have tried eating healthy more nutrient dense foods like fruits and veggies but it still makes me feel the same. Any one know what it could be?Â