What Causes Light Period With Sickness After Missing It For Months?

I missed my period for 3 months haven t seen a doctor and now it suddenly came and lasted a week but wasn t heavy at all , and no two days later I am really sick ! I m very light headed, stuffy nose, my throat is dry (but I feel like its caused by breathing through my mouth and no use of my nose) and I m very sleepy ! What is wrong with me ?