Yes I agree. I plan to keep them separate for the next 2 weeks or so just to settle in. I have to deworm them and check for mites before I release them with my original birds. I have always been told it's best to keep new birds separate for a few weeks. I am glad I decided to since I have a possible ill bird. I talked to the person I got them from and the climate in Columbus Georgia is hot and dry . Where I live it's cooler with humidity or alot of rain so I'm thinking this might be a factor. I didn't notice any odor coming from the head of the "sick" bird and there are no other symptoms besides sneezing, congestion, and clear fluid coming from the nose.
You should not be worming your chicks. Too early if they are the two week olds. Also, when my chickens hit the ground at 12 weeks, we wait to deworm.
There are also beneficial worms and their bodies need to be able to identify them cell wise first.
I have a question... is the chick shaking it’s head?
If it is vet.
If so, suspect Infectious Laryngotracheitis
If not, I say Bronchitis caused from change in environment. Went from hot to cold. Hopefully you will be able to find a vet to exam them.
If you do not see blood coming from their nose, then I would try and recreate their environment. If they are the two week olds, they should be in an area that is 90 degrees. They need to settle down and see if once they regroup what color is the discharge then. Next, I do not know what you have but also think about the size of water hole available to them. It may have simply sucked it up through nose and now it is coming out. If you put something dusty it will take time for them to get the dust out. Chickens sneeze too.
So... if it was me, I would keep both of them together, heat, maybe wet crumbles to consistency of brown sugar to make sure it isn’t inhaling fine powdered crumbles LIKE my new bags have right now! Keep eyes clean and nose wiped. Monitor eating and drinking and a tiny bit of behavior watching and it may be fine. The discharge color will be the factor to watch and if it is Serious respiratory she would not be eating, lethargic and blah. Once you see that, be worried then.