Lymph node dissection

Was diagnosed with squamous tongue cancer 10/6/22. At the time no sign of cancer in the nodes on the PET scan. Had surgery 10/26/22 to remove the cancer lesion on tongue. Was 3 mm depth of invasion no sign of it in the blood or lymph channel. It was positive for perineural invasion. Recommendation was not to take lymph nodes out but to get left over high grade dyplasia off of tongue and then do radiation. 12/6/22 had sugery to remove dysplasia. Went in for first radiation 12/30/22 Dr felt my neck and felt a swollen node. Went in for CAT scan with contrast and it came back with 3 abnormal nodes. Now scheduling surgery to remove lymph nodes on left side a selective neck dissection and then radiation. Currently waiting for the surgery. Looking back to see where I went wrong. I guess I should have insisted they take the nodes at the first surgery to make sure they were cancer free ? Has anyone heard of this happening before ? Currently have one lymph node that is painful and feeling down about not getting nodes previously removed. I have heard that cancerous lymph nodes are not typically painful. Any feedback on what I will be going through with neck dissection and radiation and should I have had nodes taken out at first surgery ?