What is the lump on my nose after Botox injection?

I would say that lumps or bumps 3 months after Botox would be very, very, very uncommon. Usually when there is a small lump or bump right after, it's from the injection itself and it's a bit of swelling that occurs. This will go down quickly and I have never seen it last 3 months. It is possible you have something else at the end of the line there, like a milia or small cyst. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."