BFP AFTER Surgery!!!

So I have endometriosis and had a laparoscopy ten days ago, they removed the endo tissue and a cyst on my ovary. They did a pg test before and it was negative.... Obviously! 
But I had no bleeding after the op which I always do and no period! (It was due the day of the op) the last few days I've been feeling pretty weird, had horrendous headaches and constantly needing a wee! So I took a test and got the below, now I haven't had sex since the op so I must of been pg  during!! Now I'm freaking out about all the drugs and damage ive done!