If you are experiencing a pink spot and pain in your back and left side of the abdomen during your 5th week of pregnancy, it is important to consult with your healthcare provider as soon as possible. These symptoms could be indicative of various conditions, such as implantation bleeding or ectopic pregnancy, which require medical attention. Your healthcare provider will be able to evaluate your specific situation, perform any necessary tests or examinations, and provide appropriate guidance or treatment. It is always better to seek professional advice rather than self-diagnosing or ignoring these symptoms.