Why do my legs, arms and fingers keep twitching?

My legs and arms have been twitching randomly but consistently for the past hour or so. This morning i took a 30mg capsule of adderall, and about 1 hour before this started happening i smoked like 4 bowls of weed. i felt fine after that but i drank 2 beers and started feeling twitchy and got a headache. i dunno if it was the combination of adderall and alcohol or what. does anyone know what this might be?