My Dad Went To Bed To Take A Nap And

My dad went to bed to take a nap and woke up not being able to move. He laid in his bed for 3 hours not being able to move but remembers everything that happened. He gave the whole timeline to my mom. My mom found him and his body was stiff as a board. He was taken to the ER where they thought he had a seizure. All blood work, tests and doctors said nothing shows up. It’s been two weeks and he is still having extremely hard charley horses. What is going on with him.