It's not possible to know precisely what's responsible for the condition of your chick unless you get a necropsy done if/when the chick dies. I highly recommend it. If you got the chick from a private breeder, it is possible their flock has a virus or even Marek's that you've imported into your flock.
Besides the possibility of it being Marek's, there are other viruses that cause the same symptoms that are passed through the egg from hen to chick, resulting in these early onset symptoms and early death, if not death in the egg before the chick even hatches. These viruses are all extremely contagious, spread on wind currents as well as direct contact.
Right now, you can try to treat the symptoms with vitamins and maybe antibiotics and see if there's improvement. The fact your chick has labored breathing leads me to believe vitamins aren't going to fix it.
But should the chick die, it's very important you get a necropsy so you know what you're dealing with. It could affect your entire flock.