Inducing Your Anxiety?

Just curious if anyone out there can attribute there first anxiety/panic attack to a particuliar event and of those people how many can attribute if any to Prescription/OTC/Street Drugs ...the reason I ask is I had never had a history of any Anxiety/Panic or any other mental disorder until about 16-17 nearly immediatley following a new found ephedra/amphetamine addiction...the habit didnt last long but the anxiety did. It now seems that anything just shy of aspirin will make me feel like i'm toxifying my body and trigger a massive anxiety attack and on the rare occassions when i do consume and prescription usually pain killers or even Robitussin DM (ANXIETY SUFFERERS BEWARE ANY DM COUGH SUPPRESSANT CONTAINS DXM A COUGH SUPPRESSANT THAT IS KNOW TO IN MODERATE AMOUNTS TO PRODUCE VIVID HALLUCINATIONS AND I CAN PERSONALLY VOUCH THAT A SINGLE DOSE GAVE ME THE WORST PANIC ATTACK OF MY LIFE) ...when i do ingest these even at legal prescribed doses my body is almost instantly thrown in to shock with anxiety. So back to my original question can anyone attribute the anxiety back to a prior addiction whether it be Alcohol/Scripts/OTC/Street Drugs? Please Elaborate