My sister had red bumps and welts all over her arms legs. she said they burn it like a mosquito bite. this started last night when high fever stomach ache. what is it?

It is possible that your sister is experiencing an allergic reaction. Some common triggers for such reactions include medications, food, insect bites, and latex. Some of the signs and symptoms of an allergic reaction include:

- Red, itchy, and swollen skin

- Hives (raised, itchy bumps on the skin)

- Swelling of the face, lips, tongue, throat, or other body parts

- Shortness of breath

- Wheezing

- Dizziness or fainting

- Nausea or vomiting

In some severe cases, an allergic reaction can be life-threatening. If your sister is experiencing any of the above symptoms, it is important to seek medical attention immediately.