Weird happenings... faint line + odd symptoms

Hi ladies, feel like I'm going mad. ttc no 1,on cycle 5. AF was due last week and turned up reasonably on time, but was super light and short, turning in to brown spotting which literally has never happened before. On Sunday morning I woke up with crazy sharp pains in my left side, have had cramps on and off since. This morning I took a train journey which I do often and was hit by a huge wave of nausea! It was like nothing I've experienced before apart from when massively hungover! Have taken 2 tests, the first superdrug one had the faintest of lines and one this morning which was a BFN. What do you think??