TSS Question?

First off, I know TSS is really rare and was probably way overhyped back in the 80s and 90s. Also, sorry if this is a little TMI.

I’m a 19-year-old female, pretty healthy and active (5'5", about 120 lbs). I live right next to the beach and have been using tampons since I got my period at 10. I’ve never had any issues with them until today.

It’s day 3 of my period. Usually, my periods last about 6 to 7 days, with the first two days being super heavy and day 3 kind of unpredictable. I work as a lifeguard, so I was outside at the beach most of the day. I made sure to change my tampon regularly—none stayed in for more than 4 hours (for reference I work a 8hr shift).

After work, I went swimming—both in the ocean and the pool—for about an hour. When I got home and took a shower, I put in a new tampon.

Not even 20 minutes later, I suddenly started feeling really sick. I got this awful, pounding headache and felt super hot. I figured I was just tired from the day and took a nap, but when I woke up, I felt even worse.

This has never happened to me before, and it came out of nowhere. Just to be safe, I took the tampon out and switched to a pad. What’s weird is that the tampon I took out was still really dry, which was surprising because earlier in the day I had used two super absorbency tampons that were completely full (and this last one had been in for at least 2 hours). The one I had just put in at home was a regular absorbency.

For what it’s worth, I’m 100% sure I don’t have a lost tampon or anything like that.

Right now, I still have a bad headache and I feel overheated. My hands and feet are sweaty, and I just feel kind of off. I took my temperature and it was 99°F—not technically a fever, but definitely warmer than normal for me (my baseline is usually around 95°F).

I know the odds of this being TSS are super low, but I can’t help but worry since I’ve never felt like this after using a tampon before. Should I be concerned? And if I still feel sick tomorrow, could it still be TSS? Or does this sound like something else entirely?

Thanks for any advice!