I HAVE RECENTLY HAD TYPE A FLU. BEFORE FINISHING TAMIFLU,

i HAVE RECENTLY HAD TYPE A FLU. BEFORE FINISHING TAMIFLU, I ADDED MUCINEX DM TO MY REGIMEN. AFTER FOUR DAYS ON MUCINEX DM I STARTED HOCKING UP A GREY, FIBEROUS/GELATINOUS GLOB ABOUT THE SIZE OF A QUARTER. THIS HAS HAPPENED THREE TIMES. THE LAST TIME I PUT IT IN A ZIPLOCK BAG AND FROZE IT TO SHOW MY MD. HOW SERIOUS IS THIS?