Sore periods after giving birth

My baby is 11 weeks old and I have my second period since giving birth (although for my first one I bled for a lot longer than a week but I assume it was my period cause I had stopped bleeding after giving birth) anyway, I have been trying to wear tampons but it’s so sore, like a pressure feeling. Is this normal? It’s the tampons that make it sore, I assume it’s normal? Should I not wear tampons or if I can deal with the discomfort is it ok to wear them? It won’t do me any harm?