Weird chemical type smell in fish tank

Question
I've had a gourami and a plecosthamus (can't spell) in a small tank for several months and have cleaned it a couple of times.  Recently after I cleaned it I noticed the water was cloudy and had a horrible smell that got worse every day.  I thought maybe it was the plastic tank corroding or something so I moved the fish to a glass bowl and cleaned everything again really well.  On the third day the same thing - cloudy water and really bad smell.  I haven't done anything different.  What is going on and how can I fix it? Please help!  These are my 12 year old grandson's fish that I am caring for since he moved out of state.  He will be here to visit soon.  Plus I can't keep cleaning and changing part of the water ever few days.  This can't be good for the fish.  Are they sick?  They act ok.  Sorry this is so long.

Answer
Hi Deb,
Have you changed all the water in the tank?  If so your tank is now recycling, and it should be okay in a couple of days.  If not, check your ammonia, and nitrates.  If you have ammonia and nitrates in your water, this could cause it to be cloudy.  Ammonia is the number one killer of fish.  It could be bad bacteria in he water.  I do not know what kind of filter you have.  If you have a filter with a sponge, and carbon, change all the water, buy new carbon, and a use sponge from the Pet Store.  A used Sponge has good bacteria, and it will recycle your water fast.  Fish need good bacteria to survive.  Take the ammonia, and nitrate test.  You can buy these at the Pet Store for a small sum.  This will tell you what is wrong.  If you cleaned out everything including all the water, this is not good.  You must always leave some old water in the tank.  Always rince a sponge with the same temperature as the water in the tank.  If you rinse it in hot water, you will kill all the good bacteria fish need.  Before putting your fish back into the tank, you will have to check the water to make sure it is safe.  
It could also be that the town put chemicals in their water.  Your local Pet Store could give you more information on this.
Your fish are not sick as yet.  Check your water first with these kits, and if it is ammonia or nitrates do partial water changes until it is safe.  If you have not taken all the water out of the tank while cleaning, it could be recycling, it this case, let it be, and hopefully the water will clear up in a couple of days.  It is important that you take these tests.
Write back to me with the results, the size of the tank, and the filter you have, so that I can help you more.  I also would like to know if you have live plants in the tank.  
Hope this helps
Lynda