What Causes Severe Headaches Along With Tiredness Post Recovering From Flu?

I had flu last week and I have recoveed now. But I have this headache since recovery 4 days back where i get sevee headache at around the same time every day. It is so severethat my eyes burn and I HAVE to sleep with loads of Amrutanjan rubbed on my forehead and a ibuprofen. Nothing else helps. If i just takeibuprofen, it doesnt help. I get a slight nausea if I dont sleep. WHat is it? Its excruciatingly painful. Please help.