Baby chick w/ gurgly breathing & sneezes

[ShannaMontana]

Hi, we got 6 baby chicks of various breeds all at the same time, and form the same vendor. The Sagitta has been sneezing for about a day or two, and this morning we realized when she peeps real loud you can hear gurgle, like she has a congested chest. What should we do? Nobody else is sneezing, or sounds congested. We only have carboard boxes for hospice, and no extra heat lamps. Should we keep her separate?
Thank you!