Cycle day 40?!?!?

S ā€¢ šŸ’šŸ’‘šŸ˜
I've always had a regular cycle 28 days every month. But I missed my period this month and I've tested but they were negative. I still haven't gotten my period so now glow is saying I'm in cycle day 40. I dont know what is happening and this has never happened before. Help!