Frequently, when people talk about progressively adding nutrients, they talk about adding nutrients at inoculation, about 33% through ferment, and about 50% through ferment. That is, say you start at 1.100 and your goal is 1.000. You would provide nutrients at inoculation (1.100), at about 1.067, and again at about 1.050.
There is a potential risk of adding nutrient (DAP, Fermex, etc) late in the ferment of the mead because you risk changing the flavor of the mead or creating compounds that may adversely affect the mead.
By all means stir it and check the temp as has been suggested. Another thing to check is the pH. Meads can tend to become more acidic as the ferment progresses and the yeast uses up some of the minerals, etc., that moderate the pH. I had a recent mead that started at pH 4 but got down to 3.1, and the fermentation slowed down noticeably. I used some calcium carbonate to bring that up to about 3.6 and the fermentation took off quite happily once again.