My 10 year old poodle/beagle is not acting herself! She is usually mildly frisky but lately she
Is sleeping a lot and has recently shaking when we have storms... as it is hot here, I haven't been taking her with me when I go in the car some place... I know this makes her sad but I DON'T want to leave her in t he car! Could it be she is just getting older?

When was her last vet visit?

Most dogs shake when it's storming. Quite funny to see my 85lb and 110lb dogs hiding under the bed when it's thundering.

It certainly could be because of her age. The heat is another reason she could be less active. But a trip to the vet could easily set your mind at ease.