Did you sleep with any open bedroom windows? Pollen counts tend to be at their highest levels during early morning hours, and grass or moss pollen could have blown in and effected you. During this time of year especially, you'd be better off closing any bedroom windows and using fans to circulate air or A/C to keep cool in Summer.
For temporary relief, you may want to take over the counter allergy medication.
Unexplained swelling of the lip and cheeks without any predisposing disease is frequently caused by allergies. An allergic reaction can occur suddenly, even in a person with no previous history of allergy.This swelling of the lip and cheeks is called angioedema.It is the rapid swelling (edema) of the dermis, subcutaneous tissue, mucosa and submucosal tissues.Symptoms include swelling of any body part which appears suddenly and comes and goes.
Diagnosis is by clinical examination and complete blood tests,electrolytes and renal function tests.Traetment is by antihistaminics and steroids.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.