As for the shaking I would get the vet to check that the dog is not in pain,some JR's do tremble but not all the time,as for moulting, if they are brushed daily with a soft brush this helps stop the moulting, also moulting might be because it is not well, and central heating will make most dogs shed all year, but brushing helps, as for food do you feed dry food or tinned,if you require more info, try this site all jr owners and very knowledgeable and friendly.if it takes time to load site try again later as I know they have been having problems, but you do get there in the end,
www.jack-russell-terrier.co.uk