Shaking is a sign of pain......Dogs usually cover it well....Once they get to the point that it's obvious, it means that the pain is extreme! Please get him to the Vet ASAP....He's in trouble!!!! Karla
You must take him to the vet as soon as you can,as it sounds serious and only a correct diagnosis would be of help and the longer you leave it the worse it could get.
And his life could be in danger.Please let me know how you go.