I am worried

So I went to visit my dad last weekend and I also helped out with extra curriculars at school. I’m a big snacker and I also eat 3 meals a day so not eating has never been a problem until now. I barely ate when I was there and I was really hungry. I only stay there for the weekend but I only would have a VERY small breakfast and a normal dinner. No lunch or snacks. Now my stomach growls all the time but I can’t eat a lot befor my stomach gets full/hurts. And I can’t eat meals or lunch. What’s going on! I don’t want my mom to think I’m trying to starve myself because I’m not. I’m actually scared.