You should see a doctor or mabey a optometrist once you are having light flashes. If there is a problem with your eyes that could cause the headaches because my left eye is messed up so im dizzy and have had a headache for almost 2 weeks now.... but i dont think it would cause slurred speech. I would say go to doc then see if he wants to send you to the optometrist.
See a doctor hun.. could be your eyes or something else, if you don't get it checked out it could get worse. Pleas get it checked out and keep us posted so we don't worry. Listen to your big sister!!! :wink: :hug: