Okay so at 4 weeks I basically stopped bleeding it turned brown me and my son father had sex It…

Okay so at 4 weeks I basically stopped bleeding it turned brown me and my son father had sex It turned pink then I started bleeding again I spotted for 2 days then today me and my son father had sex again because the blood turned brown now I'm spotting pink again why dose this keep happening ???? ( I've been cleared by my doctor to have sex . )