Bleeding this soon after your period, and only four days after intercourse, is unlikely to be pregnancy related. It's too early for implantation bleeding to show up yet. With PCOD, your hormones can trigger extra spotting or an irregular cycle on their own, especially coming off Kremson. This is most likely hormonal rather than anything to do with the intercourse itself.
Next Steps
If you want to rule out pregnancy, a home urine test is most reliable from around 3 weeks after intercourse, so waiting until later this month gives an accurate result. Since you have PCOD, it's worth seeing a gynaecologist for a pelvic ultrasound and hormone check to understand why the bleeding is happening.
Health Tips
See a doctor sooner if the bleeding becomes heavy, lasts more than a week, or you get fever, severe pain or unusual discharge.