HELP ME‼️‼️

So y’all I’m not supposed to start my period for 4 to 5 more days usually it says on my ovulation stick that I ovulate on day 21 and not day 14!! But my periods have been coming like clock work but today I got a real bad headache sharp ones and now im spotting idk what to think I took a test yesterday it said negative but im thinking maybe what if I got pregnant on day 21 and now im implantation bleeding? Idk what to think or could my period be early? This just don’t seem right cause I been taking my ovulation test kits and for the past days it shows I haven’t ovulated or been fertile could I have already been pregnant? Is the test not showing cause im not far enough along?