I have what I believe is a white oak tree on my property, it is about 50 ft tall and about 6 ft in diameter at the base. This year I noticed that the leaves did not come back as dark green as usual and about 3 weeks ago I noticed that the leaves on the west side were turning brown. Today abou 30% of the tree is brown and dead looking. Could this be Oak wilt? Can you recommend a tree doctor in east Texas? We live in Quitman about 40 miles north of Tyler.

I really hope to save this tree it is beautiful.
Thank you