I appreciate your caution, and I urge you to talk with both your son's teachers and your doctor about his problems. Only they are in a position to evaluate him and decide if he might be helped by some type of medication (under careful medical supervision).
The human brain is incredibly complex, with hundreds of chemicals working together to make it function properly. I often think of the Bible's statement: "I am fearfully and wonderfully made" (Psalm 139:14)–and we truly are. But when one chemical in the brain is missing or gets out of balance, it can affect us in dramatic ways–and medicine can sometimes reverse this. Share your concerns with your doctor, and talk also with parents who have faced similar situations, so you know what to expect.
At the same time, do all you can to let your son know you love him, no matter what problems he is having. Divorce is never easy on children, and he needs your constant encouragement and support. The Bible says, "Encourage one another and build each other up" (1 Thessalonians 5:11).
The most important advice I can give you, however, is to urge you to open your heart to Christ and seek His wisdom for the struggles and decisions you face. God loves you, and even when you feel discouraged, He is with you and will help you.