What are the optimal settings for a QS:Yag for treating post-inflammatory hyperpigmentation?

I've been having laser treatments to remove my tattoo which is now around 75% faded. However, I've had issues with a lingering brown colour, which I've been told is likely PIH. We've tried going over it again at higher fluences to try and break down the excess melanin, but this just seems to worsen it for a time. I've read that a few sessions using low fluences can sometimes help to lighten it, is this the case? If so, what would be the optimal settings? Thanks in advance.