Kidney stone question

I awoke last Monday with excruciating pain on the right side of my abdomen, ended up in the ER,after a ct the  doctor said I had a 1.5 MM stone that was passing, they gave me pain meds and sent me home. I had a couple of brief episodes of pain later that day and then everything was good. Strained my urine for 2 days and got 2 pieces of something the size of sand very small that's it.  Doctor also stated I had another stone in my kidney same size. I felt fine for 2 days then without any pain I started to have to strain to urinate and when I do urinate I pass very little urine and it's very uncomfortable. It has been like this for 4 days now and I am looking for an informed and educated guess on what might be going on. I don't have insurance and can't afford another ct unless it's absolutely necessary any help would be appreciated.