Here you can use breadcrumbs to shot the path your user took (and so, letting them manage how they can come back to previous part of your shopping).
Google online shopping store use a dropdown menu from top with the breadcrumbs techniques. You're sure that your users know where they are and how they can go back to previous part of the shopping website that way.
Amazon Implement both of them, but the dropdown menu come from the left side and the breadcrumbs is not exactly presented the same way (using more "human" language to show the user how he got here).
My opinion : Take inspiration from those. Combine breadcrumbs in a way that your users can understand it (Amazon is for everyone, google merchandise store is maybe more for "Tech Addict" people?) and dropdown menu that stays. This way, you'll never lost anybody and they can navigate through your shopping website the way they want (Autonomy in Self-Determination Theory) to find what they want (Competency)
Never forget to test what you're trying out to see if your design is adapted to your users! (if they're tech addict, show them this in a way that they are used to!)