Discoloured tooth

Summer is just over 2 1/2 and tomorrow i'm taking her to the dentist (for the first time) as one of her front teeth is discoloured, like a grey colour! i've only noticed it for a few days! my partner said on sunday that she fell and smacked her mouth so i'm guessing thats why this tooth is discoloured as every other teeth are bright white! She is also saying it hurts but whether it is or not i'm not sure as i think she's picked up on me looking at the tooth etc and showig people. When i rang for an appointment they receptionist said that had happened to her son and that it is nerve damage and that the tooth is dead!

I hate dentists and i'm trying to be real strong but i'm really worried for her! i've even got my mum coming with me (so so sad!!!!)

Has anyone else experienced this with their little one's and please give me some advice so that i can make sure my fear doesn't rub on to Summer!