I gather you don't have a teacher, but are you following some particular method from a book or web site?
All kinds of physical and mental things can start to manifest as you build up a little bit of concentration and mindfulness. If you can't find a teacher (which would be my first choice) then I would advise picking a book and/or web site of a particular teacher and following that.
For example, here is a short course by Gil Fronsdal, with audio and handouts, and there are many other talks by him on the site: http://www.audiodharma.org/talks-intromed.html
The introductory chapters of Ajahn Brahm's book on meditation, Mindfulness, Bliss, and Beyond, can be downloaded here: http://www.bswa.org/zencart/index.php?m ... c4a683449d
And there are meditation talks by him here (among others): http://www.bswa.org/audio/podcast/Guide ... ns.rss.php
Saturday, 17 November 2007 6:00 p.m.
Friday Meditation with Ajahn Brahm at Dhammaloka Buddhist Centre Western Australia.
Those are two quite different approaches. See if you think one or the other suits you.
Each teacher has his/her particular approach, and ways of solving problems. If you are starting out it is much less confusing if you stick to one approach for a few months.