Rash? Help pls 🙁

I have this really bad red stuff on my vag and i genuinely can not figure out what it is. It is painful and I started a new pad brand and I'm wondering if that could cause this. It's been a few months but this started bad the last 2-3 periods. I just noticed the rash. I am sexually active but there's no question about other sexual partners, as we are only having sex with eachother and are togethr 24/7. What could this be from and how can I fix it? Before I saw the rash thing I did use vagasil but I have before and it never did that. I also started BC like 5 months ago. Pls help. Thanks. This is also very out of my zone to post such a thing but I don't have anywhere else to go.