I've had this light green odorless discharge come out and i've been having cramps all day . i am also in my fertile window . what might this be ?

Std: With a greenish discharge and pain you better see your doctor for exam and treatment

While this may be: normal, you should be checked for an infection. It is normal to have changes in vaginal discharge which vary with timing of the menstrual cycle. Normal discharge is clear or whitish with minimal odor. So any color, even if odorless, should be investigated. Trichomonas infection can cause a green discharge. The fact that you also have some cramping at mid-cycle also suggests a check. Good wishes:)