I have adhd-pi with sct and severe fatigue; i have little to no help from concerta, adderall, or vyvanse (lisdexamfetamine) for my add. i have heard desoxyn might help?

A small chance : There is a small chance that Desoxyn (methamphetamine) would help if the other stimulants and or amphetamines have not helped. Also stimulants are often not very helpful in inattentive adhd.

Maybe: Make sure you have had complete blood workup for fatigue related issues, consider sleep study if you wake tired or other sleep apnea symptoms, also ask your doctor about Focalin (dexmethylphenidate) xr or nuvigil.