@wmcool
I too take Magnesium at night because of sleep issues in place of melatonin. But I was taking it for almost a year before my OLP made it's debut just about a yr ago.
I am a fan of essential oils, Love them in the diffuser and use Frankincense quite a bit for my shoulder/neck area.
I just found one that is recommended through Dr Jockery, a natural medicine guru that addressed OLP , He recommended from Vibrant Blue Oils, (they have a section on Immunity) the Parasympathetic, and I found the Thymus support that I'll try, to support the T- Cell along with a sleep aid oil. I will back away from the Magnesium for now just in case it's not helping.

I am curious what oils you used as a mouth rinse?

I have found that Cleure toothpaste with coconut oil is the least troublesome of the many many I have tried. I did just buy a sample pack of Fygg but haven't' started on them.
A couple weeks ago I came down with Covid and suddenly I have mouth sores I had avoided since before the holidays. A little research of Covid showed (OLP), a chronic inflammatory condition, due to immune system reactions to the SARS-CoV-2 spike protein and high psychological stress can cause a flare up of OLP. I didn't' see that coming but will be cognizant of these types of things in the future. I am still learning and always searching!