What could be a cause of having a low grade fever for two days and also i get headaches all the time?

You don't say what you mean by low grade fever. If you ate talking about in 99-100 range this is a normal variation, If you are saying 100.5 or higher, then that is truly a fever and most commonly is indicative of some type of infection. If fever lasts more than a week, or other symptoms develop, see a doctor.The list for chronic headaches is huge.Best to see your primary doctor to sort that out.