tightness in the throat can be a sign of stress, just like other stress symptoms. I've read about it in my studies, and experienced just a touch of it myself, but not bad. There could be other reasons though....since I'm not a dr., i wouldn't know.
It could be related to the heart IMO. During PVCs, ventricular tachycardias and in some forms of SVT, it's common that the timing of the premature contraction is just right to cause a backward pressure wave (called a Cannon A wave) forming in the throat.This gives a tickle, tightness and even (in some case) a neck bulge. Specifically, when the right atrial contraction occurs when the tricuspid valve is closed, a Cannon A wave will occur in a jugular venous pulse. This is not dangerous in and of itself but the arrhythmia could be. You should take your mom to a cardiologist and have the irregular heartbeat diagnosed in the context of her overall heart condition. Probably, it's just PVCs, which in a healthy heart is harmless.