HELP! NO appetite,no strength,sleepy?

My mom is 47 years old. she's been feeling quite ill for 3-4days.everything tastes bitter to her, every time she bends her body or head,she feels her head swollen and hurt,she can't even cook.my mom used to love talking to me,but now even I use all my efforts to arouse her interest,she still does not feel like responding to me because she feels too weary, My mom lives a regular and healthy life,she does not smoke or drink alcoholic,and she did not eat anything wrong,she is careful with her diet.Worst case,she does not want to see a doctor because it would be too expensive. How could such a thing happens to her,what my mom might have?thanks!