Period ended then came back after ?

My period usually lasts 5days. It came friday so my last day shlda bn weds. It looked like it ended, there was no more blood flowing. Me and my boyf had thursday and right afterward and I bled. Now its friday and there's still light bleeding. Extremely light. What could this be? Why would I bleed for an additional two days aftr it left? Has this ever happened to anyone? I want to know if he was the cause or not. Is this something I should seek medical help about?