What Could Headache, Cold Feet With Fever Suggest?

Hi. I am a 52 years old womad. Yestarday I began feeling ill. First an intense headache, followed by cold hands and feet, shivering and confused. I thought I had low blood sugar so I ate a PBJ sandwich but didn't helped vvery much. Later on I got 100.4 fever and was trembling. After drinking a Jamba juice and a sandwich I improved. Whaat is wrong?