Flying fish

Mine did the same thing once.

It turns out that if your blades are unbalanced and then you track them they vibs are really bad. But sometimes if you get them out of track it counter vibrates the unbalance blade. It is strange really. Just make sure your blades are balanced. Start with the factory setting for the mixing arms. And get some even number blade grips on there, like 4-4. Makes them easier to track.

Good Luck