5 days post op breast reduction areolas cracking. Can this be possible areola necrosis? (Photo)

Hello and thank you for your question,
From the photos you have provided everything looks normal in the healing process. The cracking you are seeing is just dryness from your recent surgery. You may want to check with your plastic surgeon to see if moisturizing is an option at this point in your recovery. Best of luck in the rest of your healing!

It doesn't appear that there is any necrosis of your left nipple.  It would be normal to have more discomfort after reoperation, since a second breast procedure, and internal manipulation of the breast was required.
It is likely that after several weeks to months, the weird feelings and discomfort of the left breast will resolve, and the nipple should look more normal.