The system that prepares food for absorbtion into the bloodstream is the digestive food. It makes sure the food in the stomach is broken down.
It honestly depends. If this is you, or a friend, I would suggest to see a doctor to be sure because they are the only ones that can make a professional diagnosis and provide the best advice.
My input would be: either a coping mechanism or hallucinations.
Either way, it's nothing to be ashamed of and the sooner you seek medical advice, the sooner you can get a legitimate answer.
If a proteins shape was changed it may be able to do its function to do being unable to fit in all blood vessels/arteries and the shape change may of hindered its capability of carrying nutrients it needs to transport, etc.
for example:
If a hemoglobin (red blood cell) shape changed, (this is normally called sickle cell) the red blood cell would be to unable to travel through the body with ease and easily clog bloodstreams. Also, the hemoglobin will not be able to transport as much oxygen throughout the body.
D. stimulants because they make you hyper and talking fast and convulsions means hyperactive