Tampons can be a real pain and it legit took me years to figure out what worked for me, so you are not alone! I would recommend trying a different type of tampon. I have major issues with tampax, and applicator tampons in general, I can always feel it and most of the time it feels like its about to pop out! I am a big fan of the Lil-Lets brand non-applicator tampons, altho they are a little fiddly they are much smaller and far more manageable imo. That would be my first suggestion but if you’ve already tried it or you find that it doesn’t work I would suggest seeing a gyno to get some more insight into whats going on. Tbh it could also be the stress of trying to get a tampon in and what it could mean if you can’t get it in that might be causing your muscles to involuntarily tense up making it even harder for the tampon to go in? If that somewhat resonates with you I would try taking deep breaths and really relaxing yourself before trying again. Good luck !!!