Doggy troubles..

TayTay • ☂
My dog Charlie passed away after being by my side for 17 years. I miss him everyday and I feel heartbroken that he got sick :(
I have another dog which was his mate and she's 15 and she howls every night and whines til all hours. They are both outside dogs and we can't get another dog. 
I'm so sad as I don't know how to fix my other dog :,(
Any advice I'll accept :(