Aamber888, you have asked a very good question. I do not know the answer, however.
We know that MMS only lasts about 1 hour in the body, so that is not a problem. The key question is how long does THC remain in a body? With so much information available on cannabis these days, someone should know the answer to this question.
Also, I don't know if THC will actually reduce or eliminate MMS as I have never tested them.
To be on the safe side, it would probably be best to use one of them and not both at the same time. If you don't get the expected results from one, then try the other.
Let us know what you decide and if your health is restored from the ailment you are working on. Thanks!