Replying to Fog spot on fisheye lens

So because I ski in a dome, the temperature change from being outside to inside is quite big, so when I bring my camera in to film, all the lenses fog up which is fine because they all adjust pretty quickly. The only lens that doesn't fully adjust is my fisheye, there always seems to be one spot of fog in the very middle of the lens that I can't get rid of and the reason I can't get rid of it is because it's on the inside of the lens rather than the outside.

Is there anyway to fix this? should I try myself or should I take it to a camera shop?

Also I can post a video of the footage from it when it has the fog spot if it helps.

ty in advance :)