how long activated mms keeps

I have been making up a four ounce bottle of mouthwash with 40 drops mms and 120 drops of acv, after it is activated I add water. It takes me
several weeks to use because I just
pour a little on a toothbrush. It still smells strong and has a yellow color. Are these indications that it is still good, and if not, are there any indications to look for; or should I just keep it for a certain amount of time?