The egg smell MAY be your cat, its not a leak that would smell like exhaust not eggs. a clogged/worn out cat smells like sulfer do to the chemicla reactions that happen within the cat. I had this problem once I put on the cat back (no codes) but once I had a HF cat put in it lasted for a bit but I think it was only burn in since it also happened on the other ride I had a new exhaust put on. Take it to the dealer and bitch. the EPA regs for emission control devices I believe are 80K miles, so they may replace it no $$ if that fixes your problem great if not you ain't out no $$