You might be subconsciously worried about it hurting so your body tenses up. Definitely take your time easing back into it 😊😊
I am experiencing the same. We've tried a couple of times. It did get easier as it went on. However I noticed I was really uncomfortable wearing a tampon when I got my period. I will go to the GP and get checked out.
If it’s like a tearing pain definitely speak to a gp , if it’s uncomfortable take your time to ease back into the rhythm so start off gently and slowly until it gets comfortable also use lube or anything that you like to use the lube will definitely help with that discomfort and also try different positions maybe it’s the positioning that can be uncomfortable