I 1st guessed this could be a slicer issue, does the object look normal in preview?
I would try to reduce retract distance first, set it to 1mm @ 45mm/s.
Did you calibrate your machine well?
Maybe this helps 
Summary: Extruder calibration a must
I 1st guessed this could be a slicer issue, does the object look normal in preview?
I would try to reduce retract distance first, set it to 1mm @ 45mm/s.
Did you calibrate your machine well?
Maybe this helps Summary: Extruder calibration a must