I have a stomach problem that i need help with. can anyone help?

my stomach has been feeling strange and im in a little bit of pain. i haven't been able to eat right for a couple days. every time i eat i feel full after the first couple bites. then later i will get hungry again and still will feel full. it started a couple days ago and i think its because i ate some crackers that were not good. but i also am lactose intolerant and drank milk a week ago. it is making me not sleep right. i will wake up around 3 in the morning feeling starving. it has also been making me poop but only a little at a time. i usually do it 1 time a day, but now its 3-4 times. i haven't gone to the doctors yet so i thought i could figure it out on my own, but i haven't matched anything i have looked up. it isn't always hurting it will just randomly happen.