Strange altitude drop and course change.


I have followed Air France flight AFR65 from Los Angeles to Paris on the 23rd October and after flying for 4hrs and 20 minutes Northeast at 37000 ft at500mph.One minute later it had dropped to 24900ft at 290mph and heading Southeast for 12 minutes before climbing again to 37000ft at 500mph and resuming its direction of Northeast the track on the map shows this clearly ie going back approx the way it had come and then reversing again on its normal route. Can anyone explain?