4 yr old female acting very strange

by Sally
(Ireland)

Hi, we have 2 Jack Russells (sisters) we have had no problems with them. They are happy, lively dogs who are very loved. One of them has been acting very strange for the last 4 days. She is not running around like she usually does, no tail wagging, she waits to be lifted on to furniture ect when before she would just jump & she seems scared. She is eating, drinking ect normally & we have checked for any sign of injury. It's very hard to explain but she is just not herself at all. Her relationship with her sister hasn't changed so it isn't that. Also her ears seem always back & she shakes. I would be very grateful if anyone has any advice.