The dog misses you , so obvious.
Is there anything new in your life? New addition to the family, less time at home, family chaos or arguments. Pets can be affected as well. Give the dog LOTS OF LOVE!!
Leave a radio on low it may help and if you are away for a long time can you have a reliable neighbour or dog walker visit for awhile and take the dog out.
Also the dog is getting older and may just not be able to hold it as long, just like people.
At 12 years your dog is a senior, so keep it in mind and don't let the lovely thing stay alone or outside by itself.
Keep us posted.
Cats only have nine lives because they stole them from dogs!Teehee