What Causes Pain In Chest Along With Throat?

For about 2 years now my mother once a month starts feeling pain in her chest (in the center) and her throat at the same time. but the pain is getting worse. Its so extreme that she can't even try to get someone's attention and ask for help. the pain continues for about half an hour. unfortunately her Doctor have done ultrasound , taken X-ray and blood tests, etc. but haven't found much and her pain is getting worse. if you have any other questions please let me know and i will ask my mother and get back to you as soon as i can. she doesn't speak much English. her primary language is Persian