need help with a 6 week chick

Im really new to this so maybe wait for someone else's advice but have you checked its crop for blockages or impaction? (I'm not too sure if this is correct but i think i read some where that olive oil can help with blockages) do you stay and watch how much it eats? I had a sickly small chick that wouldn't grow so i took him inside and feed him scrambled eggs mixed with starter feed and he soon improved with a heat lamp and attention.
I hope someone with better advice can help you

 

If its eating and pooping normally (meaning OFTEN since its a chick...lol), then the crop is most likely fine. So, compared to others of the same breed and age, it appears skinny? Or are you only comparing it to the younger, chubbier chicks? And are you certain of the breed? Because some breeds are just skinnier looking than other breeds.
Personally, if it eats, poops, and is active, I wouldn't worry about too much about it. The scrambled eggs suggested is always good, especially for lagging appetites - but that doesn't seem to be an issue here. But they couldn't hurt, since they're full of protein and yummy.