Sudden Symptom Arrival after only minor symptoms presented

My fiance has been having minor off and on nasal issues (both runny and stuffy nose symptoms yesterday & today), but nothing that caused problems or concern. He developed a minor sore throat earlier today, but still no concern or other symptoms. He said the sore throat was from his nasal issues and subsequent mouth-breathing to avoid the runny nose & stuffed nose symptoms when they occurred while he was sleeping. He did not sleep well because of the nasal issues.
Then, late this evening (around 8-9pm AZ time), his right tonsil swelled quickly and was visible from looking at his throat externally, his sore throat began becoming much more painful, and his nasal issues worsened (he went from occasional nasal discharge & congestion that would usually persist for a short while and then would lessen or stop, to complete congestion while still being extremely runny), and he was still tired from a bad night of sleep and extremely long day. He finally passed out on our couch around 1am and I can't say that he has "woken up" but he keeps mumbling and talking in his sleep (some of it is nonsense or really garbled, but sometimes he'll say things that do make sense, like responding to a question someone asked) and moving around a lot, and he started shivering off and on around this point, so I covered him up with a blanket and have been watching him.
He has the occasional sleep problems, but never like this.

Not sure if the following could be related:

Last year, he was getting fairly regular extreme migraines, each time requiring a hospital visit due to migraine-pain induced dehydration. It took us 5 hospital visits in a 2-3 months period for one of the doctors to questions the cause and he told us that the headaches were being caused by a sinus infection my fiance did NOT display any symptoms for that was suddenly causing swelling and the migraines.

However, he has not had this happen since that last hospital visit a year ago.