Hope somone else can provide some information to you, but in the meantime: What size is this tank, what were the readings after your water change (including nitrAtes), and what is the temperature?
If your nitrItes are 10ppm (ml/L) that seems very high; while any amonia is never good for fish, my recollection is that a reading of <.25 with a ph of 7.4 wouldn't necessarily be that critical. A nitrIte of 10 would be critical as would a super-high nitrAte. Could your tank be going through a mini-cycling?
If after the water change the numbers didn't drop to safer levels (in my mind <60 nitrAtes and <2 nitrItes), I would probably do another large water change to get the numbers down. I have also been told, numerous times, that additional areation can help fish handle higher nitrIte levels (as well as higher temperatures). Not sure if it is true but I usually follow the advice and keep the airstones running. If I thought it might be stressing the fish I would probably try to turn it sown to a minimum airflow rate before I would shut it off.
Good luck - and hope this helps until someone can give you better information.