Lots of different choices for wormers- may be helpful to do a search for "wormers" on this site.
As for whats normal with intestinal lining, I would say one or two is normal but past that it may be an indicator of a problem. Did they get into anything they werent supposed to? Did they spend any time outside on the ground? Have you given them any new treats?
A week ago, one of mine had a few poops that I thought were intestinal lining so I dismissed them as anything to worry about. After 4-5 days though, the hen got worse. Now 7 of my 8 chickens are having the same symtoms to varying degrees. Im not saying thats whats happening with your chick, just that an intestinal lining poop is apparently not as "normal" as that website has led people to believe.
Edited to add: also, what brand of feeed do you have them on?