The nasal septum is a pretty tough piece of tissue, even if it’s pierced through the optimal ‘sweet spot’ & stretching is paced with the body. I didn’t find my septum stretching too pleasant- the day it was done it was fine, however it felt hard and tender and sore like a nosebeak for a week or so afterwards every time.
I mean, we are stretching a hole in a part of our face that doesn’t usually have a hole. It’s perfectly normal to experience tenderness and even a bit of lymph around the area for a week or so after the stretching. If the pain gets worse, or just doesn’t go away, it’d be worth talking to a trusted piercer.
Good luck, happy stretching! :)