You are experencing a bactera bloom probably due to the first fish's death. For a 7 gal
tank two fish is at least one to many.
clowns are a bad idea. they will quickly (a month or two) outgrow the tank and you will have to get rid of them plus they will overload your little system as far as bio capacity.
NO anenome's. Your tank is to small to have the stable water they need plus I doubt you have the proper lighting for them.
If your temp flux's that much i would say your very close to the uppther threshold of temperature. This is another problem with small tanks in that the water temperatures and conditions can change in the mater of minutes vs with larger tanks they are somewhat more stable.
I would do a water change of 20%. Check for ammonia and nitrite before and after the water change aswell.