TTC going nuts!!

I am 18dpo had light spotting around the time of AF (brownish) then had a very light 2 day bleed. Nothing like my period! Before the bleed I felt nausea, really over tired,metal taste in mouth, bad head,cramping & really sore breasts. I Still feel tired have cramping but no other symptoms. I got BFN on hpt. What's going on???