Nitrite / fuzzy little white balls

Question
I have a 10 gallon starter tank I bought.  I let it run for 4 to 6 weeks and then added three rasbora's.  The next week I added 3 fancy yellow guppies.  The following week I added 3 black balloon fish, and a little noodle looking algae eater.  I have lost one of the rasbora's and a black balloon fish.  My Nitrite levels and PH levels have been very high.  A week ago over a 4 day stretch changed out 25% of my water every day, and added a third live plant. The Nitrate levels have gone down but the pH and ammonia levels are still high.  I have also noticed a lot of these little white spike looking cotton balls.  I change about 25% of my water a week with a gravel vacuum but feel like my tank especially the bottom is extremely dirt.  Three days ago I lost another fish (black balloon).  If you see that I have done something wrong or have any information to give me I would appreciate it.  This is my first fish tank, I don't feel like I am to far of from having success.  Thanks

Answer
HI Travis:  You need to clean the gravel with a gravel vacuum... those white spike balls are old food that is growing fungus... clean up the gravel, change 20 percent water and if you can get some "dirty water" from the aquarium store... that would help a lot.  You have also changed too much water so your tank is likely to start to cycle again... the dirty water will help prevent that... You are losing fish to ammonia/nitrate poisoning.... please keep me posted... dave