“Professional incompetence” means lack of ability safely and skillfully to practice homeopathic medicine or one or more specified branches of homeopathic medicine as a homeopathic physician, or to practice as an advanced practitioner of homeopathy or as a homeopathic assistant, as applicable, arising from:
1. Lack of knowledge or training.
2. Impaired physical or mental capability of the homeopathic physician, advanced practitioner of homeopathy or homeopathic assistant.
3. Indulgence in the use of alcohol or any controlled substance.
4. Any other sole or contributing cause.