Hi, I had gone through your query and understand your concerns.
These are the possibilities for the situation.
The first test could be false positive(rarely but happens). May be implantation
failed at very early stages. You have mentioned bleeding for four days and mostly its a period. So please try to accept it and go on. If you still have doubt, Visit a gynecologist and get the scan done if you dont get the period next month.
Hope this helps. Thank you