Flu since the 6th day after my period was due, test positive!

Hey girls! I'm pregnant! Actually not expected and I hadn't really been thinking about it. But around the time of my expected period, I got the flu. A really bad flu. I was under the covers, everything in my body hurt including fever. And my lower back, oh my, it was unbearable, like I had hot coals sitting there, such pain! Fever up to 40°C. Paracetamol didn't help. So I told myself, just rest it out. But after 2 days, I thought, damn, I should get my period now. I counted back on the calendar and yes, it should be coming now. I looked and saw nothing. I thought it must be delayed because of the flu or something. But after a few days, still nothing. But I was so sick that I didn't leave the house for a test. I scoured the internet for info on flu and menstruation. But it drove me crazy. So much different info. Until I was 6 days late and tested... before the control line even appeared, the test line was bright red! I was in shock. But I thought this must be a faulty test. Such a quick result can't be. I put it away in the closet. The next day, I thought, damn, the test... I went to the store and got another one from a different brand. I thought, maybe I'll get a different brand (who knows). And when I got home, I tested (in the evening) and yes, exactly the same! Happy!! But the flu is still present. But luckily, the pain is much less now. It's mainly still in my throat and nose. But what I'm wondering is, is this flu a symptom of implantation, or am I just coincidentally catching a cold? I don't remember my first pregnancy. I did have a stomach bug then though.