almost passing out from tampons/suppositories

im 20 and have never been able to successfully insert a tampon because i get really light headed. my gyno recently gave me boric acid suppositories for bv but every time i insert it using the applicator (it’s like a tampon), i nearly pass out. i get really light headed/dizzy, loud ringing in ears, and can barely hear. what is the cause and is there any way i can stop feeling that?