Ochronosis vs Rebound Hyperpigmentation with Hydroquinone / Retinin A use? (photo)

I have been using Hydroquinone + Retinin A for less than a year now. Within the last week only, I noticed what looked like a hyperpigmentation of my forehead only. I have been using HQ off and on. IE) I would go weeks without using it, and then start using it again. My question is whether I have exogenous ochronosis vs. rebound hyperpigmentation. How can I tell the difference? Does the duration of use matter? PLEASE HELP . I've been extremely sad as having ochronosis permanently is depressing

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