Hello, I Have A Almost 9 Year Old 10 Lb

Hello, I have a almost 9 year old 10 lb mini doxie. She has been sensitive to being picked up. But what I thought might be her back bothering her, I wonder? She acts the same if you touch her underbelly while picking her up. Today when she used her pee pad, I found what looked like a seed. When i picked it up it broke up. I'm concerned because we had a Shih Tzu that dealt with bladder stones for 7 years, she passed. Her stones were hard and all different sizes. Can this be a kidney stone? Today she passed 2 Seeds or stones. She's peeing ok. Any suggestions?