Disease is different for a homeopathic doctor. What is seen in conventional medicine as the diagnosis or disease, is in homeopathy is just a symptom, or group of symptoms. It can be compared with the "diagnosis" of a fever in the medieval ages. We now know that a fever is not a diagnosis, but just a symptom of many different diseases. It is so well known that it is not easy to imagine that "fever" once was seen as a real diagnosis. For homeopaths this is the same for normal diagnoses like "bronchitis', "diabetes" or "depression".
In homeopathy many more aspects are seen as symptoms of disease. For instance, the food desires are normally seen as just a matter of taste. In homeopathy they are seen as a compensation of an imbalance, a disease. Sometimes we understand it, like the desire for sweets can be seen as a desire to be loved. A desire for salt is understandable in the case of a patient in the state of Natrum muriaticum, which is made of table salt, but often the reason is not understood. Then the symptom can still be used for diagnosis. It is not essential to understand something in order to be able to use it.
A homeopath will never tell a patient that he is not sick or "there is no problem". When someone says he is sick, he is sick. The feeling of being diseased is already disease.
What is disease
In treating patients one wonders more and more what disease really is. Where is it coming from? A first answer is that disease is dis-ease, not being at ease. The healthy inner tranquility is disturbed and unrest is replaced.
Why should unrest arise? Where does it come from? Conventional l medicine mostly sees disease as coming from outside, from bacteria, viruses traumas and the like, so those causes are treated, but does it really give relieve? In chronic diseases it turns out that most symptoms are "treated", or better said "counteracted". The disease isn't really cured and the patient has to take medicine for the rest of his life, meaning that it's only palliated.
In homeopathy it becomes clear that disease comes from inside. In this respect homeopathy is akin to Buddhism. There the cause of disease is seen as coming from desires and the disappointments and fears arising from them. The idea that things have to be a certain way results in sadness, anger and frustration when things are not the way as expected. The solution is to free people from delusions, visions of how things should be. In Buddhism this is done with meditation. In homeopathy with remedies. In this sense it can be said that homeopathy is a scientific form of Buddhism. It helps people to free themselves from their delusion and desire.