vyvanse is speed. Doctors have no business putting a child on speed. It is amphetamine and very addictive. People on amphetamines can mimic paranoid schizophrenics. He is telling you he will commit suicide over his grades at school because he is craving the drug and will say anything to get it. Please don't put him back on it. Pray for him and trust in God for an answer. I love kids and cant bear to see them suffer. Try Christ, He love you and you son more then your mind can imagine. Please have faith for you sons sake. Let the Lord be your guide, your son may need to be weened off this medicine slowly, he may be suffering, but that just my guess. Follow Christ.
How did your son do on the Vyvanse? Did it help him focus? Was he better behaved and more accepted by his peers? Have his grades plummeted after coming off? If this is the case then coming off the drug has had a big impact on his life and it could cause depression. Any type of stimulant can cause you to be more confident and promote a general feeling of well-being. When you take that away there can be some rebound depression. I would definitely seek counseling for him.