Under eye skin is very sensitive. Under eye pigmentation could be due to dry skin, allergies, thin skin through which the blood vessels are visible and thus looks darker, pigmentation and many more. Glycolic acid is a very strong agent which can cause side effects of not used under the right guidance
Next Steps
Kindly dont self medicate. take healthy food, check your multivitamin like vitb12, iron and get the deficiencies corrected. make sure u r not dehydrated by taking plenty of fluids
Health Tips
visit a dermatologist for further evaluation and management