Can someone tell me WHY BABIES CRY FOR NO REASONS??? OR THEY JUST WANT SOMEONE TO CARRY???

These few days, I noticed Kayden will cry for no reasons, usually in the middle of the night (from 12am onwards)... At 1st, I thought he was hungry so I made his milk milk & let him drink...He like entertaining me by drinking abit, and used his little tongue to push the teat out of his mouth... Then after awhile, he CRIED very loud so I 'forced' the teat into his tiny mouth... Then cried again... So, no choice had to carry him up & calm him down... I really don't wanna to spoil him by carrying him up whenever he cries, but no choice...

A while later (about 1/2 to 1 hour) he cried AGAIN... So I thought his diaper was soiled badly with his poo poo, and cleaned him up... I just don't understand why babies will cry when even changing their diapers... Don't they want to be clean?? Or is it JUST my Kayden that's being cranky? Haiz... After changing, he kept quiet again & off to his dreamland... But after a while, the whole drama started again... Haiz...

Sometimes I just wanna hit him real hard (I really mean REAL hard) on either his buttock or his thigh for crying for no reasons, but I don't really bear... I DID hit him hard on his thigh once, cuz I simply can't take it (all his crying & nonsense) & he cried REAL loud till my hubby gave me a fed-up look... Ok, I'm @ fault... I shouldn't hit him hard, but sometimes it's not that I want to hit him one ma... I'm a bad mummy right? Ok, I promise NOT to hit Kayden AGAIN...

I just hope that this episode will be gone soon, if not I'm sure I'll get depression...

Pics of my baobei: