Baileys(Cocker)strange behaviour..

[chico2]

I am concerned with Baileys behaviour lately,the neighbors Cocker we've been walking for several years now.
Twice last week,she refused to go outside,she would sit there shivering ,her whole body shaking.
It happened again yesterday,but today she was happy to go for a walk.
I told the owner,but don't believe they will do anything about it.
She(Bailey)is deaf from an ongoing earinfection and still has smelly muck in her ears.
Could she be shivering that badly,because she's in pain???
They think she also has a touch of arthritis,beeing about 13yrs old.
Does anyone know why she shivers like that and her heart is beating like crazy..? Not every day,but it has been 3 days where she just refuses to come out