The reason Perez retired, returned and retired again in disastrous Japanese GP

The Red Bull driver endured a terrible race following first-lap contact with Mercedes’ Lewis Hamilton which forced Perez to make an unscheduled early pit stop for a front wing change. 

Perez was then hit with a five-second time penalty for a Safety Car infringement as he entered the pit lane. 

Fighting his way back through the back, Perez then collided with Kevin Magnussen, tipping the Haas driver into a spin at Turn 9 following a late lunge. 

That resulted in Perez picking up more damage to his Red Bull (as well as another five-second time penalty) with the Mexican making a second trip to the pits for a nose change. 

Shortly after Perez was heard complaining that his car “doesn’t feel right”, before he was told to “retire the car” on Lap 15. 

Red Bull then sent Perez back out into the race on Lap 40 in order to serve his second five-second time penalty, presumably so that it doesn't carry over in some form to the next race in Qatar.

After serving his five-second time penalty on the next lap, Perez was told to retire for a second time on Lap 43.