Not all ailments of the body can be explained simply because an individual is unhappy. There are many individuals that develop cancer that are very happy, and there are also many depressed individuals that seem to outlive those that live joyfull lives.
A depressed individual will in fact be less likely to live a healthy lifestyle compared to someone that is not - such as not exercising, not eating healthy, drinking excessively, lack of interaction with other people. What gets most people down is the belief that the their problems cannot be fixed - which is probably why so many antidepressant drugs exist. Rahter than trying to work out the actual problem - it is covered up or bypassed with a chemical.
healing the self can be one of the most difficult feats for a human being to accomplish paradoxilly. We seem to have all the right answers for everyone else, but not for ourselves. To feel better she will have to work out her problems and try to heal herself. There really is no other way. Having someone that is willing to listen to you can be the most therapuetic of all. Soemtimes when we tell otehr people our problems we can really see the error of our thinking processes and how self-defeating they really are.