My baby is a smelly baby too!
My other two did not smell like this either.
Mine is an EXTREME sweater!! I've actually been worried cause he sweats so bad. Even his feet sweat which I didn't think babies feet did. I will bathe him, and then the next time he eats his head will break out in sweat beads and the smell is back.
The smell isn't teenage boy stink, thank goodness, but he's just not the sweet smelling baby that most people would expect him to be. LOL In fact, I'm really worried about when he IS a teenage boy!! Whew, I don't know if I should let him sign up for sports then. LOL
I'm actually probably gonna mention it to my doc the next time I go just to "be sure" it's not something I should worry about.
ETA: I also wanted to say that we co-sleep, and the place where his head lays on my bed will stink so bad that my other kids actually complain! I am always Lysoling the area trying to tone it down, but every night it is the same. He will wake up and the spot under his head is so big and wet it looks like he's wet the bed, but it's the sweat from his head.