As from the history i think it is white dot on cornea and not on iris
, because iris is inside the eye and cornea is the outermost part of the eye.
Since you are using contact lens
and pain and photophobia
both are present, corneal ulcer
or corneal infiltration should be the first suspicion and first diagnosis, until unless proved otherwise.
You should stop using the contact lenses till the pain and other symptoms come down, start antibiotic eye drops and preferably consult your ophthalmologist for right diagnosis and right treatment.