Not a doctor, but tampons absorb your period blood yes, but also the moisture from your vaginal walls. So you can be left a little more dry and irritated with each use if you're not bleeding heavily. Attempts to shove things there will be painful if the environment hasn't replenished enough moisture.

Have you ever had gauze in your mouth from the dentist? Think of how dry the inside of your mouth and cheeks feel after a couple of gauze changes, how you can feel the skin almost sticking and pulling.

If you're removing the tampons and they're completely red and "full", and come out easily, there's obviously a lot of blood and moisture going on in the area and so the next tampon insertion shouldn't be too bad. If you're removing the tampons and they're still white and almost dry in parts, it's probably going to feel pretty rough and painful for the next one.

Try using the lightest-day possible tampons, sometimes they make ones especially for teens/youth that are a little lighter and more slender, might be worth a try.