8 days late

My last period was Jan 7th and I’m currently 8 days late cycle day 37 which is odd for me because it usually runs 27-30 , and earlier this week I saw light brown discharge only when I wipped and only last a day and a half not even enough to stain my underwear I’ve been having a lot of aching stiffness in my back and light nausea but the major Symptom is dizziness my sugar is dropping more than usually . But I tested 3 days ago and got a BFN thoughts ????