a virus
not getting enough sleep
spending too much time in the sun
bacteria under the skin
doing too much exercise
stress , anxiety
an allergy to pollen
an allergy to dust or animals
headache, fever, aching muscles
high temperature, nausea, dizziness
a painful muscle contraction
difficulty breathing, wheezing
can't stop yawning
runny nose, sore eyes, sneezing
spots and red lumps on the face and neck
hay fever
overtired