Ugh, I had the same thing happen to me. I had a huge pregnancy belly and after delivery was so surprised to still have a flap of fat hanging over the incision area. The flap of belly fat caused the incision area to stay moist and I ended up w/ a gross rash also. I don't know if you're lucky enough be back to a flatter stomach, but if you're not then try this:
My OB/GYN told me after a shower to dry the area off, put an anti-fungal yeast infection cream (miconazole - i just bought a generic cream) on the incision area and put a panty liner (absorbent side down on the incision) in-between the flab area to wick away any moisture.
I felt silly with a pad in-between my belly fold - but it totally worked!! It didn't heal immediately, it took some time, but it stopped hurting and itching.
I swear I wore granny panties for at least 2 years. I couldn't stand to have the regular style panty elastic touch my incisions because it was still so sensitive.
A word of advice. DO NOT: go up & down the stairs a lot, pick up heavy things, strain to get something from a shelf, etc. Ask for help or ask someone to do it/get it for you. I am pretty independent and didn't ask for any help. Silly me: took me longer to heal, and I ended up w/ an ugly, ugly scar because I thought I was super mom and could do it on my own the first few months.
Good luck & take care of yourself!!