YEAST INFECTION I think help??

I think I might have a yeast infection. For some reason every time I wear a certain thong (it’s to small on me I and it’s not lace like the hard plasticish kind, i tend to get one) so me being dumb it was one of the last pair I had (laundry) so I wore it usual day, it kinda like gets in between my 🐱 lips and ya sorta irritated and some discharge. Thannn I was like oh it will go away. I later on that night had sex with my boyfriend and during it I felt pain and like burning. Also very itchy (this all started (Tuesday night) and since than it felt alittle better and I thought it was gone and than I had sex again with my boyfriend couldn’t even finish it hurt so bad. And today it still hurts less on the outside but inside still burning and kinda swollen. He can’t even stick it in lol it will be a burning sensation. So now I don’t know what to do? Yesterday I tried coconut oil and that helped alittle (that’s why I thought it was healed today but I guess not) I have had an yeast infection before (like 8 months ago) and Ik that monisit (idk how to spell it) that didn’t work cause like my vag literally won’t let me insert it. Especially with this one the like opening won’t let anything in. So anyone have suggestions ? Btw I’m 17