I'm On Day 13 Of My Tonsillectomy. This Evening I

I'm on day 13 of my tonsillectomy. This evening I have been coughing a lot, which is not something new, but I have actually been spitting up some mucus which I have never ever done in my life! I feel like my mouth is so full of mucus I'm going to drown in it. What could be causing this? I go for my post-op appointment on Monday. Thank you!