I had the treatment 2 years ago. Dentist suggested me to have a crown on the tooth. ( molar) but during the appointment for crowning I went back to my college hostel so I didn't get time. My tooth is weak and has a large hole. It moves when I move it. Do I need to crown it? Will I have to go through the painfull root canal treatment again?

If the tooth is that bad, holes and wiggles, you may need to remove it and get an implant. Why would you crown a loose tooth? Root canal should not be a painful process with properly injected numbing and possibly gas.