What Causes Short Periods Followed By Back And Stomach Pain?

hello, I used a tampon for the first time this past weekend I am normally very heavy my first three days then it lightens up for the last four days always giving me a complete 7 day period. This time I only bleed for those 3 days and i have not seen any blood pass the 3 days. now I am having irregular back and stomach pain that i have never ever felt before as well as dizziness and headache. Whats wrong with me? I fear the tampons somehow clogged me and that is what is causing the pain. Could that be true?