Woke up with chills and fever, is it due to flu shot?

i have had post nasal drip for two days and treating it with nasal inhaler and nedi pod. last night I woke up at 230 am with chills aches and pains and a fever of 101.5. two hours later i broke out in the sweats and when i woke up in the morning I felt fine and fever was gone. I got my flu shot in late October 2017. What was this ??

Age: 64
Medications: sivastatin, lisinipril celexa
General Information: no