Hi all,
I have Chronic Lyme and started MMS with 1 drop
and third day I got a mouth ulcer. Something I
didn't have for years.
Could this be a temporary elevation of a already
existing condition?

I've never heard of MMS being the cause of such a thing. MMS is a wonderful healer of many things, including using it with brushing your teeth and to improving the health of your gum. Have you ever had any reactions to lemon juice? or any other citric acid?
Did you use the right ratio for mixing your citric acid in the little bottle?
Ever had any former problems with herpes simplex 1 before?, [sores on the lips or mouth]
Considering that diseases effects people in a variety of ways, perhaps some added stress has brought back former sores?
Just don't know my friend, could be any number of a dozen things... Can't beat a lab test to have it checked out though.
You might also consider using the capsule method of taking the MMS1 too...
Be well and enjoy the right-use-ness of life~They come together..

One of the early Rife frequency treatments I gave my wife, who has Lyme, resulted in many blisters in her mouth. I am fairly certain it was die off from the Lyme as a result of the treatment.

It did happen one other time, but to a lesser degree, a couple of years later. I started using a different frequency, and apparently it hit some other form of Lyme which had a similar result.

Yours may also be related to die off of Lyme or a virus, near the surface of the mouth. If it is, it should resolve itself in a short time.

Dan