Anxiety is a known side effect of stimulant class of drugs. It is inherent to their mechanism of action that they modulate mainly noradrenaline (increases level in some brain areas while increases in others) which causes anxiety. So, you need to choose any other drug with action somewhat similar to stimulants and also have anti-anxiety action (i.e Bupropion, Venlafaxine or clonidine)
Next Steps
Consult your psychiatrist to choose an alternative to stimulants having anti-anxiety action
Health Tips
Never self-medicate