What Do White Rock Like Particles In The Stool Indicate?

Question: Hello. I am in relataively good health, and my hubby & I do not have health insurance. We eat healthy, occassional drink, no smoking, and workout 3-5 times per week, and drink pretty much only water. Not on any prescriptions, just take vitamins and some natural supplements. In the last 2 months I've experienced pain in my lower left back, and could feel things moving. I felt that I was experiencing my 1st kidney stone. I never knew if it passed, but I was not doubled over in so much pain. I was able to manage at home. Along w/ that I had a terrible yeast infection for 3 weeks, and was able to treat w/ monistat. Haven't had since early 20's. I am 40. During this time, I was experiencing something new as well....I pooped out a white, rock hard the size of a lima bean twice, it was inside what looks like a pod, or like texture of lettuce wrapped around it. 2 of those w/in 2 weeks. Today, I just experienced it again. About the width of a nickel, but skinnier. I put in a ziplock baggie. I just don't know what to do. I'm still having pressure and a dull ache mostly on my left lower back. When I had the kidney pain/stone (possibly)...I could feel pain and movement, like people experience coming thru eurethra, and pulling sensations or brief cramp in bladder. Due to all this I missed my cycle for the 1st time in my life. I ususally have cycles that last 5-7 days, and heavy. And start from the end of last one, to 1st day...is usually 19-21 days. I keep it charted on my calendar. My hormones seemed to be thru the roof as well, and never have had children...I did take 2 pregnancy tests as well. I tell ya, 2 months of pure crazyness. Any idea if I have some kind of infection, what these pod things are? Thank you so much for your time. XXXXXXX (Oregon)