Dendrobium bellatulum brown leaf

[tree1]

I have a young Dendrobium bellatulum as show, as you can see the tip of the leaf has turned brown and limp. It started right at the tip and has worked down.

You can see it has some much smaller leaves, they are prospering and have grown since I bought the plant.

I keep it in good daylight, bearing in mind we've had some very nice days the last week I'd say bright sunlight. I'm trying to maintain roughly 55 - 65% humidity. Temperatures have been around 75 - 78 Fahrenheit. I haven't been over watering the plant... but I might have been under watering it!

Any tips much appreciated.

(added question... would you feed a plant this young every time you water it?)