First off, please read this about
implantation bleeding.
Secondly, no you should never wear a tampon while pregnant.
Third, some women do bleed for the first trimester of pregnancy.
And last, but most important. It is imperative that you get to your doctor immediately. This may be nothing of any significance, but could be a miscarriage, or something even more serious. The internet is no place to truly diagnose your health. We can only provide helpful suggestions. So you must get to your doctor ASAP!!