I lost 4 fish while in Cali!!

#1
I got home last night from California and saw that my 3 lemon tetras and my juvi female zebra angel were dead and my plec is missing! I looked on the ground everywhere and behind the tank and in the tank, but he/she is gone:( I think that they died from my filter clogging. The tank was cloudy when i got home and all of my fish are still gasping for air even after i unclogged it!!!!:mad: My 55G tank should be done cycleing in 2 weeks(it was set up in October when we first started to move) so i will be getting some fish for that tank and if my fish don't get better soon, idk what i am going to do to make them feel better. Can anyone help me...:(?