Do delayed periods with negative beta-hCG and urine tests indicate pregnancy in a female with PCOD?

Hello doctor,

I had an intimate moment with my friend where we had finger pleasure (with pre-cum in the finger) and no penetrative sex, but ejaculation on the outside. The last period date was the almost two months back and we indulged in this activity around fifteen days after the last periods. The periods are delayed till now and it is delayed by 50 days. Last week she did a urine test on the kit for a couple of days and it came out negative. She took the B-hCG test almost 25 days after the incident and it was 0.1 which is negative. From saturday night she is having spot bleeding and today from the afternoon till now, she has not got bleeding at all with stomach cramps and vaginal discharge at times, and vomiting and nausea persist at times. What do you think can be the issue? Is this implantation bleeding or what to understand out of it? She has PCOD and irregular periods.