My 2 cents worth: The PLA is not cooling enough to stay rigid when the next layer is being put down, therfore the nozzle+viscous_pla is tugging on the still rubbery lower layer. The first layers profit from the release of heat to the bed (extra cooling), the higher layers don't.

Try lowering feedrate to 40, temp to 190-210 range (or even down to 180 at 40 mm/s feedrate). A minimum of 2 shells also may help as these are put down at a slower rate and support each other.