This isn’t something that can be easily answered. It sounds like your appetite is just flawed, which can be caused by multiple things like; depression or anxiety, your diet, medication, lack of sleep or a bad sleep schedule, lack of exercise can also make ones appetite seem overly present or non existent.
I have experience with that but that’s due to my own gastrointestinal and mental health issues .
I don’t believe you need to see a hospital if it’s just your appetite, however if you’re not eating it can land you into the hospital and cause to develop more issues like malnutrition and anemia.
So, I’d say make an appointment with your pediatrician and discuss these symptoms. And in the meantime evaluate what standard parts of wellness you may be missing such as adequate sleep, proper exercise, proper meals with proper nutrients from all food groups (I recommend eating things involving ginger , or something warm which boosts appetite but avoid high sodium intake or fried foods) speak with your doctor if you need help choosing which foods to eat, and try to engage in stress relieving activities. Little things that are out of routine can mess with appetite
But I recommend just making an appointment with someone soon , try having multiple snacks or small meals through out the day and maybe try drinking tea between meals in the meantime
