BMW 3 Series smell of rotting cabbages

I have a 2009 Series 3 with M upgrade (2000cc) . On Sunday I made the mistake of parking Half a mile down an official "field " carpark . It rained all day and when the concert ended , it was a free for all to try and exit as quickly as possible . Several cars were bogged down , luckily mine managed to limp to the exit by using clutch control in second gear . It was a struggle and the DTC light came on several times. There was a lot of smoke coming from the rear of the car and also from the front , accompanied by an horrendous smell of rotting cabbages ? The car is performing normally since Sunday , any idea what was happening , and have I done any lasting damage ?