Its hard to tell...but is the live plant a peacock fern...if so its not a true aquatic and will slowly rot, die and foul your water.....but like I said...it hard to tell from the pic....so I maybe wrong.....
Anyway....It may take a couple of days to see any improvement if it was stress related...you might want to turn off the light for the day too
Be sure and vacuum well when you move things around in the tank-sometimes its best to not move things-just vacuum in areas that can be reached without moving anything or disruption of plant roots...
Be sure the replacement water used for water changes is within a few degrees of the tank water and Dose the dechlorinator for the full volume of the tank-double check the label for correct dosage-especially if you have chloramine and chlorine in the source water...some recommend double dose....
Keep us posted.....