Mood swings (depression) is a common side effect of Vyvanse. As others suggested, this is something you should discuss with your doctor. I'd also suggest alternative remedies since they don't cause many side effects and may provide satisfactory results (depends).
Switched from Adderall IR 60mg daily to 60mg of Vyvanse daily. Worked for a few days but now I have brain fog, depression, lethargy, no motivation, no social ability, and feel dull. Good appetite, hydration, no alcohol. Dose too low?