Thanks Takoon,a couple of people have mentioned that it could be muscular,I'll look into it more,probs find someone into sports injury massage or something.I had an mri of the head and neck and this came back as normal,but I don't suppose muscular problems would show on there.A couple of medics have said that head problems are often a mystery and things can dissapear as fast as they appear,so hopefully this will be the case,in the meantime I'll try every avenue.Thanks for your advice,cheers!