Help needed with new 7week old chicks in quarantine (something is just not right)

Hi everyone,
I could use some advice. I have purchased 2 BCM chicks from a man on Craigslist and they are approx 7-8 weeks old.
I have had them approx 4-5 days already, and something is just not right about them. There are no obvious respiratory problems as of right now, no wheezing, or drainage from nostrils that I see. I do hear the occasional sneezing form them, however my main concern is the poop. I have looked at all the poop charts and I just can't figure out if this looks normal. The color seems fine on the poop itself, but look at the area around the white paper napkin. It seems awfully stained reddish brown looking.
I have 4 other pullets that I hatched myself and they are 13 weeks and my plan was to eventually have all 6 of them together after the 2 new one make it through quarantine.
I just can't put my finger on what is troubling me about the new ones. They came from a man who seemed like he got in over his head. He may have started out with good intentions, however the brooder they came from was completely overcrowded and it reminded me of a coffin without much airflow.
He did tell me that they were not vaccinated, however were fed medicated feed.
The chicks seem unkept, I notice that they don't clean themselves a lot like my other 4 do. They are of course terrified of people considering they were always in a box and probably never had any human interaction and not a ton of light beside the heat lamp that they probably didn't need anymore being in south Texas.
Please give me your thought on the pics posted below.
I of course have other questions regarding them, however I will just focus on the poop for now.
Thanks

 

Thank you, I went ahead and started them on it today. I also decided to treat our other chicks as well. We have 2 dogs that like to go visit all the chickens. I have covered the new chicks cage, however I don't want to chance it with the dogs possibly spreading something to and fro!!
I never really though about the dogs transporting anything, I was more focused on my clothes, shoes, hands, and especially my kids!!