Throat is swollen, but not sick. had sinus infection 5 mo ago. got antibiotics. but throat has been full of mucus since. but healthy everywhere else. ?

Allergies: Sounds like and allergic problem. Try regular nasal saline flushes. If fullness persists get checked.

Allergic rhinitis?: It's possible you could be experiencing the accumulating of drainage from the back of your nose related to undiagnosed allergic rhinitis. This is a common manifestation of this disorder and a lot of people do not actually have a runny nose but instead just have a lot of mucous in their throat instead. Discuss this with your doc and discuss the possibility of a nasal steroid to stop the drainage.