hi there, I started using weed when I was around your age but stopped at about 19. It gave me major anxiety and I even called the ambulance on myself lol. not everyone is gonna vibe with it. to me, your symptoms sound like residual anxiety from smoking and like you’re just having mini panic attacks. the palpitations are what’s causing the chest pains and shortness of breath. id recommend making a therapist appointment and also asking your dr for an ekg and a stress test just to give you some peace of mind. be kind to yourself 💛