Q.Problems with my Camellia
Lots of flowers and buds but the flowers fall off quite quickly. Also, lots of brown, yellowing leaves. It is about 8-9 ft tall and does not get full sun as it is near the house facing north. Last year was bad and because of severe weather in late Nov and December (2010), only had a few flowers as most of the buds turned brown and fell off.

Certified GKH Gardening Expert
There are a few things that could be causing this such as fungus, thrips or environmental.
I would check the plant for thrips first. They are small, but would be found at the base of the flower buds. If you suspect thrips, this article will help:
https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-thrips.htm
Also, as a precaution, treat the plant with a fungicide. Increase water to the plant and check for root damage, as this can also affect how well the plant can take up water.