A lot of different situations can cause urinary crystals. The only way to know for sure is to have her urine checked by a laboratory, although sometimes cats who have crystals will meow while urinating or "dig to China" in the litterbox. Definitely get a sample to a lab and find out, not only whether there are crystals, but what kind, as there are two kinds that are treated differently. The pee sent to the lab needs to be fresh, as crystals can break down over time.

Good luck! Please keep us posted.

Love, Columbine