What Causes Persistent Headaches?

I am 19 years old, 5 3, 51kgs. I have never had any severe diseases but minor fever and gastric issues, such as gas and stomach burning sensation. I have a constant headache for the last three days, it helps when i take a dose of nasal drop. A medicine speacialist once said that i have a sinus problem. Also, i used to have this burning sensation in my stomach every morning, now it happens every time i am late for my meals. I also have urges to use the washroom sometimes three times a day, but i do not have a loose motion and i have a fever for the last three days it gets worse at night. I did not take the hepatitis A injection. Could this be jaundice? If not then what is it?