Due to your warm and humid weather I am going to guess your poor filbert is suffering from a fungal infection. The spots on the foliage and tips also lead me in this direction. First do not fertilize. Soft and succulent new growth is more susceptible. Second remove the infected leaves and fallen leaves to stop the spread of the fungal spores. If the new growth does not look healthy you may need to spray with a fungicide such as Funginex.  Follow the label instructions. Now this could also be a bacterial or viral leaf infection but the treatment is the same only skip the fungicide. The good news is that your Henry Lauders Waking stick can outgrow the problem and be healthy I future years. Or it could be dead in a few months and you get to buy a new plant. Keep growing, Marianne Binetti