Sorry to hear about poor Levi, my wee cat Bubble (female) gets recurring cystitis and when we finally got a pee sample from her....boy that was a challenge! It showed she had crystals forming,blood and some other things that shouldn't be there. Given injections of antibiotics, steriods and anti inflammatories as she does not do tablets but doesn't mind being prodded and injected by the vet!!!!!! That seems to help and also on Royal Canin SO - only available on prescription in the UK- not sure about the US? When she gets another episode she gets really antsy and vocal and sprays everywhere not great but we cope as she is such a sweetie! I hope you can find something to help Levi.....thinking of you.