huge amount of brown dropping leaves
St. Mary's County Maryland
You can send us photos of the shrub and affected foliage so we can see what you are dealing with.
However, based on your description this sounds like it may be winter damage. Many broad leaved evergreens such as camellia were affected by the cold, wind, and dry conditions with temperature fluctuations this past winter. Next fall water well before the ground freezes. Do not prune in late summer as the new shoots will be damaged by frost. http://extension.umd.edu/hgic/winter-damage-trees-and-shrubs There is nothing you need to do now. Affected leaves will drop in the spring and you should see new growth. You will have to wait and see if the flower buds are affected.
Water the shrub deeply during dry periods this growing season.
Here is our website on winter injury http://extension.umd.edu/hgic/winter-damage-trees-and-shrubs