Hyperpigmentation after tummy tuck. Has anyone seen this before? (Photo)

I got a tummy tuck on 1/2019 and had a horrible rash after my drains were removed. After my rash stopped being bright red and stopped burning it became really dark and it’s been almost 4 months and shows no sign of leaving. Surgeon said he can’t help me and dermatologists just want to give me steroids but they have not helped. Has anyone seen this before? My belly button is now turning the same color