Good luck! Speckled Sussex are very small as chicks! Especially the females. I swore mine was a bantam due to her tiny tiny size, but she's full grown and a big hen! She lays a light tan egg a day.
It's not uncommon for chicks to arrive from the hatchery to the feed store sick with the gasping motion. They are stressed easily, which weakens their immune system and are more susceptible to illness. It's the first thing I look for in buying a chick, the gasping motion. Once they get sick like this, they are carriers for life and it passes the illness to the other chicks.
My neighbor across the street bought chicks from the same store. I told her to treat her chicks and I gave her antibiotics, probios and vitamins. She decided not to treat until after one died. The rest lived once they were treated. She just didn't think anything was wrong and against antibiotics or other substances.
Good luck with your flock! I've learned so much about chickens this past year. I've done so much research on breeds and on illness.
I keep my chicken cabinet stocked with antibiotics, probios(I keep in freezer), apple cider vinegar, oxine ah, Sevin, DE, vet wrap(for bumblefoot), antibiotic ointment, face mask/gloves for cleaning, and cocci medicine(Corid) on hand in case of an emergency. I need to buy the Valbazen dewormer yet, it's next on my list.
We buy the pine bedding in the horse section at the farm store. It's very cheap. Under 5 bucks for 5 cubic feet of pine. We use it in the coop and our run is sand.
I'm sure Freckles will be fine! I love the breed. My SS Maple runs to me when I walk outside. I free range most the day.