Passing over 40 kidney stones, mostly small in 5 weeks

Male, 43, history of kidney stones for 20 years. Last Lithotripsy was performed 3 years ago. Urologist was seen in October 2009 w/xray performed. He was advised he has an 11 mm stone in his left kidney and a smaller one on the right. They had not increased in size since xray October 2008. He had decided to not do another Lithotripsy at this time. He started using an Inversion table mid January for stretching out his back.  Since he started using the table he has passed over 40 stones. It appears they could be the "dust" left from the Lithotripsy. the dust being small crystals.  What is going on?