Remedies for Joint Pain
Common signs are difficulty standing up and laying back down, can’t jump on furniture anymore, hard to go upstairs, crossing legs in the back, wobbly or shaky when standing, not wanting to run and play as much. Very common in older dogs, especially big dogs. There are good arthritis medicines made for dogs…as well as joint supplements. See your vet as soon as possible to help make your dog comfortable in his old age. 
don’t sound like artritis to me he’s licking his paw because he hurt his paw. maybe sounds more sprung to me.
He may avoid the stairs…um..limp on whatever leg is achinng him. If he licks his paw, it may just be something in there..like a need..or pin..I check his paw, and maybe then apply pressure(don’t get bitten!) 
And see if he reacts..But uh..I would take him to the vet and s/he’ll let you knowi f it has arthriis.
Our old german shephard died at 12 and in his last few years arthritis really bothered him. Signs of it including not being able to jump into your vehicle like it once did, not running very much, difficulty getting up and down steps. A lot of it is the same things humans deal with. If he has been licking his paw a lot I would say he may have stepped on something that injured it, dogs tend to lick wounds.
Usually they have a hard time getting up or walking up and down stairs. Ask a vet for a product called Rimadyl or Previcox
they have a hard time getting up from a sitting position, and if it get’s worse then they’ll develope a slight limp in their walk
Limping, tenderness when you touch the area. He could also have a thorn or cut or tiny piece of glass. I would get it looked at. m
Stiffness after getting up, unable to run and jump, soreness. DO NOT give you dog any medication at home. Take him to your vet and have the vet prescribe medication.
he may have it. have him checked out. he may also show signs of difficulty walking too