I don’t know which supp you were taking, but I doubt that 1.5-2 months could have caused your cancer.
My doctors told me to stop supp during chemotherapy because it might reduce its effectiveness and not because these supp caused cancer. When the chemotherapy was over they recommended many antioxidants (some of them helps me today with the SFN) to reduce the risks from the chemotherapy and the risks for the cancer recurrence.
I don’t know whether these recommendations are relevant to the specific supp you were taking and cancer.

How was the appointment with your Radiologist and Hemato-Oncologist ?