Post your tree question on this web page with as much detail as possible and include close-up pictures. This system is answered by horticulture volunteers, many of whom are also Tree Care Advisor volunteers.  If we cannot answer your question, you will be directed to consult a certified arborist. 
https://www.treesaregood.org/findanarborist
You may also go to "Whats Wrong With My Plant?" and select the tree category. Many common tree conditions and their possible treatments are on this webpage. 
https://apps.extension.umn.edu/garden/diagnose/plant/