Your guy needs to see his Vet for pain management......Other than the tumors in his mouth (That I personally would get taken care of quickly), his other symptoms sound like aging arthritis......Your Vet can prescribe Anti- inflammatories that will work wonders to ease his pain......
There is no reason for him to suffer like this as the meds from your Vet will give him a new lease on life.....Please, get him there as soon as you can....Let us know how he's doing....Karla
Can you take your beagle to a Vet?