I Had Strep Throat For The First Time In My

I had strep throat for the first time in my life 3 weeks ago. Was given a z pack of antibiotics. Seemed to take care of it. Again this past Sunday I got it again this time went to my regular doc. She prescribed a different antibiotic.
Early this evening I coughed and felt something in my mouth. I put my finger in my mouth and pulled out a piece of something black. The next time I coughed I coughed onto a paper towel, there were 3 little balls shaped black pieces and another little like strand.
I do not smoke cigarettes or pot.
What do you think this might be?