You want your in out number to be close if not the same. If you are dropping from 6.5 to 5.5 your roots zone is off and your plant/pot/medium needs to be corrected, this can be accomplished two ways. 1) FLUSH! Seeing that you have depleted your soil and are now feeding nutrients (btw, never got the mil. Per gallon of the trio your are giving) give your pot a good ph water till it comes out at the desired pH. This will also take care of lockout and salt buildup. 2) you can add slightly higher ph'ed water and over time it should change.
I would opt for #1. Should take 2 to 3 gal. Of water per pot, and if you do decide to flush do it in one setting.
Speaking of depleted soil and if you flush and you don't plan on top dressing, plan on feeding it liquid fertilizers, you should feed it like a coco grow.
At that point PH should be around 6.-6.3 and you will need to water to 10% runoff (around 1.25gals per 5gal pot).
If it was my plant I would ph the next feeding at 6.5, see were the runoff has come, if the plant has improved then Yea!. if the plant is deteriorating between this water and next, not improving may just consider a flush nexts.
Hope this helps.