I took my son out of high school to homeschool him. He was failing almost everything, though he loved reading Tolkein and Homer (NOT Simpson). He ended up scoring very decently on his SAT's, joined the military, who sent him to language school to study middle eastern languages at DLI. Today he's serving in the US Army with Special Forces. (Pray for him, as he is heading back to Iraq for his 3rd time in May).
It was not easy, but I'm so glad we did it.
May God watch over your son and keep him safe. May he return to his family in full health.