Stuart I went through the same thing as you. I abused some ephedra and had much similiar expierence. Turns out I just aggravated my mitral valve prolapse (MVP can be hard to diagnose and really doesnt have to be cause it just something you have to live with and take antibiotics befor the dentist visits, you can ask your doctor about this it may explains things for your case but dont read up on symptoms because you may wrongly diagnose yourself) wich I didnt know I had. The worse thing I did was read stuff on the internet all day thinking I had this and this and taking on those symptoms. I saw several doctors including an internist. They told me I was fine just stressed my heart some and now Im making it worse by assimalating problems I didnt have. What I had was an agorophobia/hypochondria. The doctor wanted to put on on xanax so I would come down because my anxiety was arrgragating my chest pain wich I thought it was me dying. I held my heart all the time. Took my blood pressure too much. Thought I had ruined my hear for good etc. WHen I finally got ove the FEAR and realized Im gonna be around for a while things got MUCH BETTER. Take a deep breathe you didnt do anything to yourself but a little strain. You will live! People have made it through ingesting much worse things and are ok. Eat right, be happy and laugh. Plus excuse my spelling and general layout of this post but just wanted to tell you that "Every little thing is gonna be allright"