Is It Normal for an Injection Site to Swell and Hurt After Days?

Age: 17
Height: 178 cm
Weight: 70 kg
Gender: Male
Smoking status: I don’t smoke

On 22nd April, I had gastritis and received two injections — one in my arm and another in my glute. I didn’t have any problems initially, but 2–3 days ago, the area where I got the injection in my glute suddenly started hurting. It feels swollen, and there seems to be a hard lump underneath the skin. It hurts a lot to touch, and even slight brushing against it is painful.

I searched it up, and apparently, some swelling after injections in that area can be normal, but I’m worried because the pain started later, and the area feels hard inside. Should I be concerned?