There is a possibility that your dog is in heat. In this process dogs normally show such behavior so there is noting to worry about. If you are positive that its not its heat period then it can be Urinary Tract Infection if it is over or less urinating than usual. But there is nothing like that then see if its vagina is red or swelled or inflammation there or around it. Take it to vet if any of these symptoms appear in it other than its heat period.