How do you know if your skin is purging or breaking out?

I used the ISNTREE Clear Skin BHA Toner for two weeks or so and I got a few pimples on my face. They were pretty big and I wasn’t exactly sure if my skin was just purging or breaking out. I was slowly getting hesitant to use the product and I finally decided to stop using it during the second week. I started using the ISNTREE Clear Skin 8% AHA Essence and my skin cleared up after two weeks. I did experience an initial purging but it then subsided and my pimples significantly reduced. Now that I’m looking back at this, I feel like the BHA product broke me out but I’m still not 100% sure. What are a few ways of telling whether a product is breaking you out or if it’s making your skin purge?