It's very natural to worry about them,they're so precious!
You can wash the puppy 48 hours after the frontline treatment..
My first cavalier had severe SM.She never air scratched or bunny hopped,or had any of the obvious symptoms that you would expect them to have.She was almost three when she was diagnosed but showed no major symptoms until she was perhaps three and a half and had lameness and became very withdrawn. She had screaming episodes which came from nowhere.
Other symptoms can be explained away as normal canine behaviour..or allergies,so the best advice is to have a good insurance policy in place should you ever need further referral.Your local vet hasn't the expertise to make a definite diagnosis,but it's good that you are aware of the condition and if you continue to have worries as your puppy grows,you'll be able to follow up with a specialist if you feel the need to.
Barley looks very sweet, tricolours are fabulous and hopefully you'll find the time to post more pics of him.
Sharing my sofa with Holly, Ivy,Lilly and Hazy.. and never forgetting our beautiful Daisy who reached the bridge too soon.