The chickens I raised were never given any vaccines. I want to know about adding new chicks to my flock. Sounds like Infectious Coryza. Haven't seen it, but it rapidly goes through a flock, very young birds usually die, older birds may all recover, but the bad news is that most will be carriers and any future birds will get it. Even after your birds seem well, you are at risk for adding new birds.
Correct diagnosis is important.
Just hope it is something else, but sounds like i.coryza. Cjeanr thanks for your response. I was thinking coryza also. I wish I would have known about adding new birds and vaccines . I'm certainly learning from experience,unfortunately it's the hard way.