H. pylori is very common, as is C. difficile. But having the bacteria does not automatically mean disease, as you have to have the pathogenic strain. Oodles of people out there with these bugs, but without any symptoms of disease.
So, unless you have a stomach ulcer or gastritis, H. pylori is fairly meaningless.
High stress levels are a HUGE factor in overall health. Life is stress, so I don't mean give up your life and join a commune. It is how you cope with stress that matters. If you don't have the greatest coping skills, high stress levels increase your stress hormones: adrenaline and cortisol. Elevated for long periods, these hormones wear your organs down.
You can't change how you are basically wired. If you are a worrier, you probably will remain one. But, you can learn to think things through, use relaxation techniques, and practice healthy living to help lower those stress hormones. Often, chronic muscle pain is associated with chronic stress. The fact that your doctors have found nothing to treat should give you a great relief, but instead it causes further worry. I'm not saying it is time to see a shrink, but if it were me, I'd be focusing on stress relievers, like leisure activities. Maybe even picking up that glass of wine and toasting life! (OK, that sounded a bit too simple, but you get my drift).
I think you will be OK.
Jan