CAJ - I cant offer you an answer for the symptoms as described here, since there are many and quite varied reasons why they may be occuring. I did just want to follow up on one point you made though......
You made a comment very common amongst posters on here - that you didn,t want to waste the GPs time. Whilst this is a laudable attitude, in general terms, anything that causes a person pain, or social embarassment, or impacts on their quality of life sufficiently to warrant posting on a bulletin board is worth going to see your GP about. Only then can you get a proper assessment from someone medically qualified and able to interact with you face to face.
I hope you are able to get some help soon.