I'm glad you asked this because it made me reread your post (yesterday was a rough day and I wasn't too sharp) and I forgot something very basic:
Has this happened before when meditating, going to sleep, or just doing nothing?
The symptoms you are describing from a purely physical standpoint can mean many things- check your blood pressure, and if you haven't done your yearly eye checkup, do it....just to be safe.

As for the heightened energy sensations, this does happen at first when you start doing energy work- everything from the clearing of blockages or just an increase of awareness can cause this- it will pass with time and practice and then you'll wonder why things don't feel as strong as they used to, which is also natural.