for the amonia test some premade water or tap water so you can see the difference between the two, i thought mine were up once but the test always turns yellow while i thought it should be clear,if you only have 2 clowns and your nitrate are up what are you feeding,mabey your putting too much in at a time not too often what filter do you have have you cleaned the filterfloss,or whatever you have in it ? if you have prime water conditioner use a cap it will nutralize the amonia and nitrates a little and mabey stall thing untill its under control.
how long have you had your tank also ?