convulsing is a medical condition where the body has involuntary (not controlled or willful actions) muscle contractions, spasms and seizures. in me this is part of my having multiple sclerosis, to find out what it is in you, you will need to contact a medical doctor.

as for the self harming acts (jerking, shaking, hitting yourself) only you and your treatment providers (a medical doctor, a therapist or a psychiatrist) can tell you why you do this and what to do about it.

here where I live this comes with many different medical and and mental health problems and even normal stuff too can cause person to want to self harm as a coping tool. to find out if you have any mental or medical conditions that are causing you to self harm like this you will need to contact your medical doctor, therapist or psychiatrist or one near you. we are not allowed to diagnose each other. all we do here is read each others posts and share whether we have had the same problems and how we are handling the problems with in ourselves.