[Little Bit of T]

I'm new to this Forum so please help me if I'm posting this is the wrong Thread.
Anyway, I have a 16 yr old non-spayed Yorkie that this past week started to act like she is in heat. She's had very little bleeding and is having the normal female desires to find a male for a friend. The symptom that is bothering her (& me) is she seems to be in pain & having urine accidents, which she has never done! My neighbor suggested Little Bit go to the Vet & get x-ray(s) for Bladder Stones. I took her to my Vet this past Thursday and she never mentioned Bladder Stones after giving Little Bit a thorough exam but did give her anti-biotics. After two days of the medicine I see a slight improvement in Little Bit but only slight. Should I take Little Bit back to get an x-ray or just trust the Vet's decision that it's just a normal late in life period?
Little Bit is eating normally, urinating normal with the exception of the recent accident, she's pooping but she's just not the same & I'm worried. I will take her back to the Vet today for the x-ray to put my worries to rest and to get her on some proper diet.
I'm looking for some help with this I'm sure Little Bit is not the first Yorkie to have this health issue.