my dog is having trouble getting up

[liltigera1]

my dog is a german shepard great dane and as of late he is having trouble getting off the floor. he is a little over weight. he is scratching himself alot (i think its from dry skin) idk if that could be a reason why he is having trouble. when he is outside playing with my other dog he is fine and he runs around our yard. he was limping a couple of days ago. does anyone know a reason or a thought and what to do