I decided the issue at this point was that her PH was too high, causing a possible irritation in the bladder. So, I began giving her a daily dose of Methigel, which is an acidifier. It's made for cats and dogs.
After a week, I cut it back to three times a week. You can't overdue this medication especially since she's eating s/o which is a wet cat food that has acidifiers already in it. The acidifiers are there to keep crystals from forming, crystals that could irritate the bladder and cause infection.
So, after a few weeks, by the end of August, I had her urine retested and the urine is now at 6, down from 7.5. Since it can't go below 6 or she may have another type of crystal form if the urine is too acidic, I am now giving it to her twice a week.
Since she's been on Methigel, we have seen a more consistent box use and rarely an out of the box incident.
So, if your HCM cat goes out of the box and the urine test shows no UTI, no crystals, try Methigel once a day for a couple weeks and then cut it back over time. If the cat's box use improves but the cat still has some issues, talk to your vet about using Valium. It's save for HCM cats. Myrna takes 1/4 tab about 8 a.m., 1/16 at lunch, and 1/4 at bedtime at 11 p.m.