Very sick month old Black Copper Marans Chick - please help!

[BlueMoon]

And I think it's a hen too. She's having so much trouble breathing, gasping, mouth often open, often rattling sound. Whole body moves when she breathes. Her eyes look awful - strained, watery, a bit of residue. she's on my lap - just sneezed.
I've tried to give her polyvisol - i don't know what else to do for her other than isolation from the other chicks. She was fine yesterday.
any thoughts? this is breaking my heart

 

[BlueMoon]

Possibly Roup (nutritional) or air sac disease?

 

[dlhunicorn]

How old is the bird? I just posted on another thread instructions for using tylan injectible ...
it might also be brooder pnuemonia (aspergillosis >a fungus) She sounds very ill :aww

 

[BlueMoon]

She's still alive this morning! Breathing is still strained, but she's a bit more energetic than last night - she was down right limp at times then.
She is about 5-6 weeks old. She was hen raised - none of the other seven chicks seem ill, but she got sick really fast - surprisingly only two days after Mama went back to the big birds.
Good news is that her droppings are normal.