My son has a canker sore in his mouth and it looks like a mini canker sore on his lower eye lid. it is irritating, there is no bump just flat. h?

May be viral: Need to see both Dentist and Ophthalmologist for proper diagnosis and treatment. Lesions may have same cause, or different causes with coincidental time of outbreak.

Eyelid?: Canker sore does not occur at the eyelids and thus they are likely different issues. If I were to guess, a viral infection would be a more likely scenario. If problem persists for more than 2 weeks or gets worse, see doctor.

Herpes of the Eye: In most cases of herpes simplex virus (HSV) ulcers resolve spontaneously within 2-3 weeks. If concerned, see GP for exam.