What is my brother doing?

hi! my name is erika. i have a bro and every night he always locks his door. and then about 15 minutes later i start hearing these weird noises. he sounds like hes hurting. im kinda concerned. it sounds like this "oooohhhhhhhhhh!!!!!" and im really worried. and then like 5 minutes later he runs out across the hall to get lotion and hes all wet. and i always think its bed wetting problems. but im not sure. hes 17 and im 12. i just want to help him out. so what do you think it is and how can i help him out? please tell me ASAP!