Root canal. Do a re root canal plz tell?

Respected Sir or mam I done a root canal last month in 27 August  in my upper teeth but while doing. A root canal I have an infection but the dentist who have done a root canal they done my root canal in an infection my root canal is been done in an infection after completing a root canal I consult another dentist they done my exray they told me my root canal is been. Not done in a proper way and I have still infection so they told me to. Do. A re root canal and I have a minor swelling in gum. But after consenting a dentist they told me it not a swelling in my gum. It my teeth bone tissue I'm sharing u a exray image and they told me the procedure of doing re root canal they will first stop the infection till 15 days and after stopping an infection they will do my re root canal is it save to do a re root canal plz tell