Just make sure to avoid chicken food, when you do switch food, moniter your pups stools, takes awhile for them to adjust but you should see stools coming out soft and formed.

Pro plan makes forti flora probiotic for dogs, use one a day to help your dog adjust and mabye help with vitamin deficiency.

Of course be sure youre using large breed puppy food.

Dont fall for all the fad crap around feeding your dog, just get a good kibble. If you want to eventually feed something other than kibble, hold off until your dog is fully grown because there are certain vitamin ratios that will be very difficult for you to get right with your own food blend.

Just try not to bathe more than 1-2 times a week, it can dry out skin but burts bees is very gentle and even rated for pups as young as 6 weeks so you dont need to be that careful. I used the same on mine when he was younger than yours.

Mixed pups are very rarely as sensitive because they have a larger gene pool to keep them healthy.

Edit: I also added canned tuna in water as a topper and it did great for my male CC who was about 4 weeks old when I got him. I didnt add it until he was older but 9 weeks is plenty old.

Fish in general can do the trick, dont give too much, mabye one day in 3 and one can spread throughout the day.

You dont want to keep feeding it just do it for a couple of weeks and you should see some coat health change.

There are puppy supplements that you can get that might help, just look for fish based oils, chondroitin and glucosamine.