No, never had a problem with rotten egg smell.
I used Optimax for first 15,000 kms and currently use Mobil. Always try to but from same service station which has reasonable turnover.
Now smell could be due to petrol,or stuffed cat or lots of short trips so cat doess not operate correctly or mixture problem
So change petrol to Optimax or Mobil. Preferably frm a service station that sell a lot of fuel so it will not be stale.
Tthen take car for a little journey so that the cat is fully warm and burn some of the crap out of the system and see what happens.
I suspect that the petrol is probably to blame as smell apparently coincided with the us of Bee Pee
"The sulphur smell from the exhaust, is actually caused by running the engine/cat convertor slightly lean for long periods and then running under a rich condition (ie going up a hill under heavy load) This is when the sulphur smell (rotten egg) is produced.
Under relatively lean conditions, the sulphur found in petrol is converted to sulphur trioxide, then during the rich running condition the sulfur trioxide is converted into hydrogen sulphide (rotten egg smell) within the catalytic converter.
switching petrol brands may help. The Oxygen sensor may also need to be replaced to correct a fuel injection mixture problem."