I can't eat in the mornings?

So I've never really been able to eat that much in the mornings. Sometimes I'm just kind of nauseous and almost always have a bit of a stomach ache in the morning, but I always try to eat something, usually just a small granola bar cause I know I need something to give me energy until lunch. But lately, even if it's not that early, like just anytime before 1:00-2:00, if I try to eat something, I immediately get really bad stomach cramps. I am a little lactose intolerant so I started getting my morning coffees with almond milk but I don't think it's the drink. I immediately get really bad cramps as soon as I take the first two bites of any food, and then I almost immediately have to go to the bathroom. I don't think I end up digesting any of it or getting any nutrients because it just causes pain and comes right out. I can only eat after the afternoons but I'm also afraid to eat too much at night cause I know it'll just cause me more pain and problems in the morning. Also, even if I eat a lot at night, not being able to eat a full lunch let alone any breakfast, I've been losing weight. And I'm already teetering between healthy and underweight so I don't wanna lose anymore. Im gonna have to stop working out if this continues to preserve my weight and also just cause I've been low on physical energy cause I can't eat until the afternoons. It's been about a week like this I feel like it should have gone away by now.