Can i see a doctor for treatment for strep throat after a week of having strep throat?

Yes: The only way to know if it's strep is to get a culture done. If it's strep, it'll still be positive even after a few days. I suggest getting the "rapid" strep and a culture (when it grows for a couple of days). That way, if it is strep but doesn't improve with treatment, you'll know which antibiotic to change to -- only the true culture can show you that. Two tests means two swabs though.

Yes and Should: Untreated strep throat in rare cases can cause serious complications. These include rheumatic heart disease which generally is permanent damage. There is a window of a week or so where treatment with appropriate antibiotics will prevent this problem. See your doctor for proper diagnosis.