Noticed Grey Substance In Saliva. Is It Due To Strep C?

Question : Hello, I went to the doctors for throat discomfort and was told I have strep c... since than its been three months and I still have discomfort and I see when I need to spit some type of black or very dark gray substance in my saliva. What is this?

As far as my throat I do believe I might have an infection. I see white spots on my tonsils, my throat is not sore and does not hurt but its the need to clear my throat. I went to see the PI in September and was tested for std's as well as strep throat and a throat culture... All were NEGITIVE except the throat culture and that was Positive for strep C... Since then I've taken two different types of medication Penicillin and another for those who are allergic to penicillin. And I seem to still have systoms. I do not have a sins drip or nasal distress... As far as my saliva it is not the color of my salvia that is black or dark gray it is very small spots that I see inside of the saliva... it looks like clear saliva with a dot/spot in it. It freaks me out to see that I know its not normal I work in research and I m a little familiar things. just to give you some idea it look like bits of the top of broccoli in clear salvia but only like a very few... I do believe in the on set of all of this on the right side of the front part of my neck, was a little swollen but the PI ruled that out. However I felt different. my lymph nodes were fine every where else. What could this be I think it might be a throat infection or Partitas. Could this be any other disease or infection?