If your on the last day of period and you are not bleeding heavy can tampon cause bumps?

It is highly unlikely that using a tampon on the last day of your period, when your bleeding is not heavy, would cause bumps. Tampons are designed to absorb menstrual blood and should not cause any physical changes or bumps. However, it is always best to consult with a medical professional if you experience any unusual symptoms or changes during your period.