Agreed, would you be able to post your current parameters? I'm assuming Ph drop or high nitrates. Have you noticed any change in behavior: ie : does the aro dart about?? Any chipped scales etc?
What have you been feeding the aro? May sound gross but have you seen the aro poo?
When in doubt tho, I'd stick with small water changes, increase the heat, increase aeration and add a bit of salt.
Good luck and keep us posted.