Sudafed side effects

A few months ago I had come down with a common cold, so I began to take the appropriate dosage of Contact C (which contains pseudophedrine hydrochloride). I remembered hearing somthing on a news program about kids my age getting addicted to it. So, like any experimental teen, I began to take double the advised dosage. I did this twice a day. I felt like a walking zombie. I soon lost all appetite and mentallly felt like i was slowing down to a crawl. I don't know if these are side effects to the drug or if I was coincidentaly going through a rough period, but I would like to know if anyone else has experienced similar responses to the drug so I can maybe get some closure on the issue.