You may be noticing symptoms of egg laying damage by the cicadas. We have had several reports of this on oak trees. 

If you are noticing browning and drooping branch tips this is called "flagging," and most likely due to cicada egg-laying wounds. The slit they generate while laying eggs creates a weak point in the branch, which often snaps in windy weather. This is a form of natural pruning and the brown tips can be removed if they are easy to reach. This can be done after all activity is finished around the 4th of July. Otherwise, the flagging twigs will eventually break-off fully and the tree will regrow from nearby buds, usually starting next spring (some tree species can resume growth the same summer). See the "damage" section on this page for an image of what to look for when inspecting for cicada wounds: https://extension.umd.edu/resource/cicadas

If this is not what you are noticing, please send photos. 

Marian