It’s hard for me to determine from the photo; I’m leaning towards a Single Head Favia or small Scolymia or Wellsophyllia.
Why do you suspect he’s not doing well? He looks fine in the photos. Without more info, I wouldnt recommend changing anything too much.
Generally: Most corals will do fine with medium flow and medium light. This is because categories that we use (low, medium, high) are all relative to average, and the average is going to cover the highest percentage of individuals. That said, too-high light has the greatest risk for coral stress. Taking this into consideration, my recommended default for anything unknown is medium flow and low-medium light... and you can adjust placement from there if more or less of either is preferred.