fizzing seems to indicate the presence of a tertiary amine (examples: BZP, DXM, DMT and its analogs... anything that has "dimethyl" in its name).
orange is a typical result for non-ring-substituted amphetamines (amphetamine and methamphetamine).
the erowid test page at
http://www.erowid.org/chemicals/mdma/mdma_faq_testing_kits.shtml
lists a few chemicals that fizz, then turn orange.
of these, the *most likely* one you have is probably 5-MeO-DiPT, although 5-MeO-DMT (not listed) may do the same thing. i've never seen these in the GC/MS test results at dancesafe, but there's a possibility.
although it's an odd combination, methamphetamine + BZP may produce a similar effect, and it's not impossible that you would find them together.
harmine also produces, fizzing then turns orange-brown. it seems very unlikely that you would have harmine, but you should be aware that harmine is an MAOI (monoamine oxidase inhibitor, which prevents breakdown of neurotransmitters in the brain) and MAOIs are EXTREMELY DANGEROUS to combine with MDMA, amphetamines or practically any other psychoactive drug.
the one conclusion that you can definitely make is that you do not have MDMA. this is a fact. you should be aware, then, that your result could indicate any chemical at all
except MDMA.