Body rejecting Tampon?

Hey everyone, sorry if it becomes TMI but I was wondering if anyone has gone through the same thing as me or can give me some advice....

I’m currently trying out tampons on TOTM (time of the month) as I’m taking the children swimming tomorrow and I haven’t used any in about 6 years but I had put one in using the applicator but now I have cramps (not sure whether it’s because of TOTM or whether my body is rejecting it) and also I’m sweating (again, not sure if it’s because of the hot weather we are having over here in the UK 🇬🇧 or whether my body is rejecting this foreign item I have just put in my body after 6 years)

What do you suggest I do? How would I know if my body was rejecting the tampon? I haven’t left it in for too long, it’s been in maybe an hour max...

Any advice welcome. Tia. X