8 week old puppies are S/N all the time in some shelters.. Im sure some of these are tiny tiny things.. Keely's breeder has most dogs over 5 lbs. Except for one puppy that was tiny tiny. She grew to be 3 lbs give or take an ounce. lol.. She spayed her because it was MUCH MUCH MUCH safer then her getting pregnant by one of her 2 , 4 lb studs by and accident..
Tiny dogs are S/N all the time
For the shaking I was also thiinking about hypoglycemia.. Split her meals up into about 4-5 meals thru-out the day.. Maybe get some honey and put a dab on her tongue when she gets the shakes?