Moving Yellow Lights awaken me on third floor

im not sure of the exact date or time as it was some 12 years ago. i do know it was the summer because i was not in school. we lived in a 2 family home and my room was on the 3rd floor, which faced the back of the house where a grammar school was. i was awaken by a flashing yellow light in my window. the lights were moving right to left in the window. it then moved to my other window. i then got up to go look at it and it left, moving unlike any convential aircraft i have seen. it moved like a rock skipping water. it was not big at all. no bigger than a car in legnth and probably no wider than 2 cars side by side. it was metallic in color and made no sound. that was the only time i have seen a U.F.O. tho i have had many periods of lost time where i will look at the clock and it will say 12:00 AM and when i look again it will say 4:00 and i cannot explain what happened in between. i also have had a scar on my side near my ribcage which no one can account for. not me,my parents not anyone.
Date is approximate.  PD