Hello!  I am sorry to hear you are having issues with your beautiful tree. 

It is a bit difficult to tell from just a few photos, but my best guess would be either leaf scorch, a gall issue, or anthracnose.  I am attaching a couple of reports and links to websites that may help you identify the exact issue.  You may have to check the branches also to help identify the issue.  If that doesn't help, I would take a sample of the leaf to your local Extension Office (if they are open - call first), or a local reputable nursery to help identify the issue.  You may also want to have an arborist come to your property.

Before you select a proper treatment or control, you will first want to ensure you are treating the correct issue.

I hope this helps!

https://hgic.clemson.edu/factsheet/oak-diseases-insect-pests/

https://extension.psu.edu/oak-diseases