Thank you for your query at DoctorSpring.com
I understand your concern.
Though the drug is well tolerated, sometimes it does show side effects such as headache, dizziness, back pain, nausea, diarrhea, e.t.c
The headache should not last for 3 days though. Are you taking 200 mg Modafinil daily? Are you on any kind of medications apart from Modafinil? What was the reason for starting Modafinil? Also any history of valvular heart disease?
Feel free to discuss further,