The area might be red and hot to the touch even if it’s just inflamed (but not infected). But if it’s infected you will likely get a fever. If it’s hard to the touch it might be just pip. If it’s squishy (my medical term lol) it could be a cyst that could need draining. I’ve had both. Hot, swollen and hard to the touch could be just pure pip that will resolve over the next few days. Or you pinned in a bad spot and it has nothing to do with the gear you are using. The next injection will tell you what you need to know.