2. 'Tickling' is literally the term for when PVC's are induced, so possibly that.
Possibly a muscle spasm as well.. need a lot more information, a much more in depth description of the sensation..
3. Possibly related to both. again, much more detailed description needed, like at least a page of you just typing everything you can think of to describe how you were feeling.
4. can be a good thing or a bad thing depending on the symptoms.