Hi Welcome in HCM. I understand your concern and I would like to say that thick phlegm during sleep indicates that you are having compromised air way at your nasopharynx during sleep. Though your tonsils are already being removed but still these are the possibilities for your problem- 1- Uvula and soft palate may be heavy and swollen. 2- Base of tongue may be swollen or hypertrophied. 3- Pharyngeal wall around laryngeal inlet may be loose . 4- Excess fat at sub mandibular region. All above may be ruled out by thorough examination and they all may be treated by expert hands of your ENT doctor. If your tonsillectomy had been done only few days back than oedema at tonsillar fossa and pharynx may be the reason and this may be treated with antiseptic gargling and anti inflammatory. Probably above answers your query if still any doubt you may re consult us. Thanks.