Nausea

Hi all, I need some advice. I'm CD27 today with no idea when I ovulated as I was on honeymoon during my fertile week. I also don't know how long my cycle is as last month it was 24 days and the month before I was on nexplanon. I have been feeling sick for the last four days to the point where I've nearly been sick and have taken two pregnancy tests, both negative. Does any one have any idea what this could be?