Hot and cold flashes, chest and stomach pain, is it anxiety?

I get pain – like an attack – under my chest where my ribs join and stomach pain, hot and cold flashes sometimes accompanied by fever and general aches. Also feel nauseous. Usually get these attacks at night. I had many of them 6 if I remember correctly. Can it be anxiety? What can it be?

Age: 40
female
medications: N/a