Hey! I'm a little concerned about the panting and shivering while although they are very normal dog behaviors they can also be a sign of discomfort and pain. You said your dog is 12 years old so he's no spring chicken and any behavior that is considered not normal could possibly be a health problem.
He's also turned off his food that's another worrying sign does he normally go off his food? I would watch him carefully, if it's hot then keep him cool if it's cool then keep him warm. Don't offer food yet just make sure he has water and try taking him outside on a lead for a pee. If he won't settle then you can drag his bedding or a blanket near your feet and try to persuade him to lay by you, it may comfort him don't forget to pet and praise him.
Don't freak out though, he might just be anxious cause your mom's not home just keep a close eye on him and if he hasn't settled by the morning and still isn't eating I'd take him into a vet you can never be to sure with older dogs! Their real sweethearts in their old age but they come with countless of problems... Best of luck to you and your lab!
have you checked your dog for ticks?
turn the heat up in your house
its called seperation anxiety. your dog is just upset that the person he normally looks to for direction is gone and he doesn't know what to do with himself.
take his mind of it by doing some obedience training or just doing something you know he enjoys like running around after a ball or something like that.
hope he settles down soon.
As Zoe said, panting and shivering can be a sure sign of pain. Especially if he isn't eating either. At his age, there could be any number of things wrong. I really think you should take him to the vet for a check up.
My chihuahua injured her back and was shivering like she was freezing to death. Wouldn't walk or stand, and growled and snapped, something she's never done. The vet said she was in severe pain. She had to be given pain medication for 3 weeks while her injury healed. We still don't know how the injury happened, but the vet said she could have been paralyzed without treatment.
Please post the results. I will be interested to hear what the outcome is.