Unpleasant physical sensation from meditation

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Focusing breath meditation on the tip of the nose caused a somewhat unpleasant muscle/nerve tightness to arise around the nose area. It started as a kind of nice vibration (almost like sensing the molecules in my nose wiggling about) but after a few days developed into more of a tenseness in the tiny muscles in the face.

This tightness isn't there after waking up in the morning, but appears slowly during the day and increases towards the evening. Meditation causes the tension to increase (and spread down to the jaws) much faster, which makes me want to not meditate. Focusing on an area other than the tip of the nose doesn't work, since this sensation is strong enough to steal the mind's attention towards it.

Has anyone here experienced this sensation before?