fever, chills, implantation?

Heather
Long story short, recently off BC, supposedly ovulated last Monday so "8dpo" in parentheses due to not knowing if my ovulation test was faulty or not. But today I'm not feeling well have a 100.38 fever with aches and have been cramping the past three days. I was told that getting sick could be from implantation because of a decreased immune system? Anyone heard of this or experience this?