I get this too. The tip of my tongue feels like it does right after I have touched a very hot drink or something. In other words, it feels like I burned it. After having this sensation for a few days, I looked at it in the mirror, and discovered that it's actually a very localized fasciculation close to my tongue tip, with a diameter of about 2 mm. It can be hard to see, because I have difficulties keeping my tongue still enough to identify the fasciculation, plus it's right under my tongue tip, so I need to lift the tongue up (while keeping it still, not easy) to see it.If you get this sensation, but don't see a fasciculation, it might be because it is too deep to be visually manifested on the surface of the tongue. I don't know. But for me, a burning sensation on my tongue tip is directly caused by a fasciculation. I cannot feel the twitching directly.