Thanks for the query..
Where is the red spot actually? On the cornea
Pupil is an aperture inside the eye and there can't be any spot on the pupil.
Are you seeing the spot on the eye ball?
It could have been a congestion ( enlargement of the blood vessels creating redness
) because of an ongoing inflammation.
Consult an ophthalmologist for a better diagnosis and advice..
Don't worry. It appears to be a minor problem only..