Went To Dentist And Had Root Canal Treatment On My

Went to dentist and had root canal treatment on my tooth, dentist said this might not work and that if not he would have to extract the tooth. Just before my holiday in June I developed a swelling and a white spot on the top of this. The tooth is always rather tender but nothing major hence the fact that I have returned to the dentist when I returned from holiday to have the tooth extracted (that was the advice from my dentist). Because it isn't hurting too much but the spot isn't going and it is a bit uncomfortable when I eat. I am petrified of having the tooth out that is why I haven't returned. Do you think the root canal hasn't been done properly.