Scarring After Plasmapen Procedure

Hi
I recently had plasmapen performed on my arm hoping to remove pigmentation. And it turns out I have cause more scarring than before.
Can someone please advise what I can do to get rid of the marks and how long will it take:
I have been using hydroquinone cream on them for about 2 weeks but the skin seem to have gone darker? I am concerned the marks will be permanent, I have fair Asian skin and is this PIH?
Can I keep using hydroquinone?

I am really stressed out because I can’t wear singlets
Many thanks