I tend to believe that your test strips are giving you bad readings. A 7 in nitrites would most surely end up in a tank full of dead fish. A water change would definately not hurt right now just to be sure. Raising your temp to 87 might not be the best idea for your fish. I'd leave it at no more than 82 unless you are fighting ick or have fish like discus in your tank. Keep us posted on your ammonia and nitrite levels, and get a master
test kit from Aquarium Pharmaceuticals if you can so you will know the true readings of your tank.
