Oaks can be stressed by environmental conditions, insects and disease. The more stress they are, the more insects find them attractive. Diseases can be those found on foliage, in the trunk or roots. It is likely that your tree has been stressed for several years and last year did not make any new buds for growth in 2015 beyond what you see. Suggest you contact your local Extension Service for a more focused idea of what went wrong and what you may be able to do.