I have been doing RCTs since 5 yrs but recently I am facing this problem  of fast canal shrinkage  after preparing  with protaper before obturation. 0.5 to 1mm shrinkage  is ok but wat bat 2 to 3 mm shrinkage  immediately  after preparing my GP goes to length prepared the first time I insert it then after I take it out and insert the second time it is 2mm to 3 mm short.

What is the solution and reason for it?