Confused - a lot!

She
I'm not sure if I'm posting in the right spot, but here goes.
​Sorry if there's too much information here, but I have no clue what's going on, and I can't sleep because I'm anxious. 
My last period was due 18.04. It didn't show. I tested 21.04 at 10pm - very clearly two lines on my first response test. I tested again 22.04 at 6:15am, again a very quick set of 2 lines appeared. I had sore breasts, a lot of bloating, stomach pains, and generally odd body functions. This all stopped on Saturday night (26.04), and I've felt 'fine' ever since, except I've come down with the flu. I waited until today 28.04 to see the doctor, thought it was a good opportunity to confirm pregnancy, and ask about this flu. The urine test taken by the doctor showed negative. He's taken a blood test, and I should get the results tomorrow, but I tested again (2 different brands, same sample) when I got home and both came back negative as well. I've had no indication that there was a miscarriage, or anything else. 
I'm really confused how I could get such a quick positive result a week ago (within 30 seconds, but now the tests are negative). 
​I'm curious if this has happened to anyone else, and if it has - what was your end result?