I Went To The Doctor For A Tooth Extraction And

I went to the doctor for a tooth extraction and before he pulled the tooth but immediately after the lidocaine injections my whole cheek began to swell. I have not experienced any difficulty breathing, just facial swelling. At first the dentist seemed alarmed and gave me some antihistamine but his said I should be fine. What could have caused this? Did he hit a nerve or a blood vessel? The swelling is local to the side I received the injections. What should I do? Right now I have a ice pack on my cheek,but 8 hrs later it still looks the same. No change of any kind of color