I Recently Went Into The ER To Get Help With

I recently went into the ER to get help with the bleeding I was having with a fibroid I have. They put me on this BC plan and it is said to help reduce the bleeding and help with the fibroid. My question is, why when I use a tampon, does my bleeding SIGNIFICANTLY increase and it takes a bit for it to slow down after, but when I just use a pad, I bleed a lot less, sometimes hardly anything. Is the tampon irritating my body right now?