I Am A 15 Year Old Girl And Have Been

i am a 15 year old girl and have been having issues with my digestive system. I do big number twos in the morning and then during the day i feel like i have to poo but i never do and what bothers me the most is the noises my tummy makes because it's really awkward in a quiet classroom. I do have pain in my stomach from time to time. I've stayed home from school because of this and it's really a struggle for me. The poop isnt like a sausage it's very crumbly. What should I do?!?!