First of all, shamanism is not a religion. It is a healing technology.
These days, shamanic healing is best used in conjunction with regular medical care. It is completely compatible with nearly all forms of medical treatment. There is even beginning to be scientific evidence that it can speed up healing and improve overall health. And sometimes, there are what seem to be miracles.
I've found that shamanic healing can help with almost any condition. It's not like western medicine, where a set of symptoms determines a diagnosis, and the diagnosis determines a specific treatment. Instead, the idea is that it's a spiritual system -- for each case you find out what the Spirits have to say about it, and what they recommend for healing. So, it may be able to help with virtually any condition.
Specifically, shamanic healing addresses the spiritual aspects of disease. Since most disease and illness have a spiritual aspect, shamanic healing is usually of benefit. Sometimes it is of great benefit. (But since some conditions are mostly physical, it may be of less help in those cases.) Since the spiritual aspects if disease are currently largely ignored by western medicine, it is an ideal complement to your regular treatment.
That said, here's a (partial) list of some of the things where we've found shamanic healing is particularly effective:
Low energy, on-going bad luck, chronic low-grade illnesses;
Feeling "not quite yourself", like watching your life go by like a movie. Post-Traumatic Stress symptoms;
Locallized pain, with no obvious medical explanation;
Sudden personality change, addictive behavior, compulsive thoughts, conditions that feel like a "curse" or "hex".
There's some background material (click here) that explains more about the ideas behind this.
Thoughout history shamanic techniques have been used to help people at the time of passing, and afterwards to be sure their spirits have gone "to the light". This includes things like "dehaunting" places and buildings, depossession work, and assisting the relatives and friends of those who have died.
Since this is spiritual work, no one is turned away for lack of financial resources. I offer completely free work in the context of a public clinic once a month (see below). However, shamanic work is more effective if there is some sort of exchange -- think of what you might pay a therapist for a similar healing, then apply a sliding scale. This helps you (and your own spirit helpers, not to mention your own unconscious) feel committed to the work, which always helps. I've found that if someone has the resources to pay for this kind of work, and doesn't because it's "free", it is often much less effective. This is serious work, and you should come to it with this attitude. Payments "in kind" are welcome.
I have met and worked with many gifted shamanic practitioners in the course of my training. I am happy to recommend them to you if you'd like to work with someone closer to where you live, or for possibly different quality in the work -- the old "personal chemistry" thing.
Sometimes I work with a team of practitioners, especially for the more complex cases. This often adds a great deal of power to the work.
The above link takes you to a short essay describing what shamanism is and isn't.