Bumps in my forehead, They are small bumps clustered together that appeared a month ago, and nothing

Bumps in my forehead, They are small bumps clustered together that appeared a month ago, and nothing gets rid of them. I’m posting this because I’m at my wit's end. A month ago, these bumps started appearing on my forehead; they don’t itch, get inflamed, hurt, or contain pus—they’re just there and won’t go away. I saw my dermatologist, and she told me it was caused by my shampoo. That was a month ago; I’ve been washing my hair more frequently and am very careful never to let it touch my face, yet the problem persists. ​ To give you some context: I’m Latina but live in the Philippines. I’ve struggled with acne for years; I actually finished an isotretinoin treatment just last November, and I’m very strict about my habits to keep the acne away. I follow the same routine my dermatologist gave me last year​ I’m really worried because, for the past month, I’ve had some comedones on my cheeks—though those seem somewhat normal to me—but I’ve never had the issue on my forehead: a cluster of many pimples and a bumpy texture that just won't go away. I take great care of my skin: I don’t consume dairy or sugar, I wash my pillowcases, and I wash my face whenever I sweat, so I don’t know what I’m doing wrong. I need help, Has anyone ever had something similar?