Tommy - did you have any damage at birth? I had forceps, an episiotomoy and a tear.
I asked on Mumsnet about tampons and was told that this wasn't normal - this would have been when ds was about 2. I got a referral to physiotherapy (which for various reasons, I didn't get to see properly until more than 3 years post birth).
It turned out that I had ZERO muscle tone in the front pelvic floor muscles. Because of my Pilates classes, I had none of the "normal" sypmton (stress or urge incontinence) as the "back" pelvic floor muscles had effectively taken over, and I had subconscioulsy learned coping techniques like clenching before sneezing or coughing. I had also lost the "cough" reflex.
I have now been doing various exercises over the last few months, some with a "biofeedback" device (a visual aid to check that I am doing them right) and my muscle tone has improved on the one side to nearly a 3 (out of 10) and on the other side, where the tear was, to a 2 (and the physio admitted that she had feared that I would get no recovery on that side). It does involve discipline and perseverance - but it does work.
By the way - be careful about the Super Tampons - unless you change them REALLY frequently, it just means that they get heavier and will fall out even easier!
Do some pelvic floor exercises yourself and see if you get some improvement - but it may be worth asking your GP for a referral to your Gynae Physio.