How come from a sneeze it can cause you to be immobile & can create lower blood pressure?

i have a friend in the hospital , no one knows what is wrong with him, he simply sneezed and right after that, they brough him to the hospital, he cant lift his head cause it creates problems with his heart & his blood pressure.so he is bound to his bed,and cant stand or walk, cause everytime he attempts to move he gets heart problems...have you ever heard of that condition..? doctors still dont know whats wrong with him, can it be caused by a pinched nerve?

There is one nerve if stimulated or pinched will cause heart problems, lower your blood pressure and that is the vagus nerve.

Death can occur in some instances when a person performs the Valsalva maneuver (bearing down to poop) or if a person is constipated and trying to poop and the feces is large. The over stimulation will actually cause the heart to stop. If it stops momentarily are restarts it is called Vaso-vagal response.

Why your friend is having this problem is anybody's guess. I would guess that his vagus nerve is involved. It may be necessary to place a pacemaker in your friend.

First you need to know, when you sneeze everything in your body stops for a brief moment.
You also release a a great deal of pressure, that is why it is not a good idea to close your nose when you sneeze.
And it is possible that your friend might even have burst a vein, pinched a neve or even broken a bone. Anything is possible.
I'm sorry I did not give you the answer you wanted, but at least you understand how these things can happen. Good Luck to your friend.