Chest spasms

Hi i have been getting these spasams that start in my jaw line, move to my head and then straight to my chest. When it gets to my chest, i find it very hard to breath properly, its almost like my chest is being crushed, and constantly spasams. It comes on totally out of the blue, and i can go from 1 week to 3 weeks in between having one. On one occasion it woke me up in the night. What could this be please. Would appreciate any advise thanks