I'm sorry to hear that you're experiencing low earnings and decreased site traffic. Making changes to your website, such as installing a new theme, can sometimes impact revenue. When you change your theme, placeholders may not all translate well across to your new theme, which has the potential to impact upon your revenue. It's important to ensure that your new theme is optimized for ad placements and that your ads are displaying correctly. Additionally, there are various factors that can contribute to low EPMV, such as traffic source, geo location, device type, browser, and niche. If you're interested in increasing your EPMV, I recommend checking out this article that provides in-depth information on how to identify opportunities with your own traffic: https://www.ezoic.com/website-ad-revenue-up-down/. It may provide some insights and strategies to help improve your earnings.