Weird Vaginal Irritation, help?!

I have the nexaplon implant. I had unprotected sex in December and he wanted me to take plan b just Incase. so I did and it obviously caused lots of symptoms. Ever since then, whenever I’m on my period I get vaginal itching. I was able to wear a tampon without it being uncomfortable. I’m assuming this is due to my pH being unbalanced. My periods were lasting 2-3 weeks, so my gyno prescribed me the pill, Sprintec, to help regulate my period about 2 weeks ago. I ended up experiencing some itching a few days after I started and that lasted about a week. I read that this can be a symptom of Sprintec. I’m having slight irritation again, minor itching and minor uncomfortableness. Has anyone else experienced this with sprintec? Or in general due to birth control/plan b?? My discharge is normal, my smell is normal, no burning when I pee and I don’t have a frequent urge to urinate. I did have sex again recently and it was not painful. Does anyone have a reasonable explanation for this. I do not believe I have an std/sti and my partner says he’s not experiencing anything out of the norm. I do plan on getting tested if any symptoms continue after my first period on this birth control. I just wanted to ask any of you guys if you’ve gone through something like this or have an explanation !