What would symptoms be if jabbed by a needle?

I have been worrying for the last week that I was jabbed by a needle...I sat on a public sofa and felt a sharpish pain in my backside. I didnt see a needle but am now convinced one must have been hidden in the chair! My husband looked for a puncture wound and couldnt see one but its now been 7 days and I have a painful pimple where I believe i felt the sharp pain and I have also come down with a horrible virus - sore throat, fever, tiredness, lack of appetite and feeling sick etc. Have I caught something???? Could it have been an infected needle I sat on? Could it have been like these storties you hear on the net etc about people planting needles in public with notes attached saying 'Now you hve HIV'