### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I ve been experiencing dizziness and leg weakness for about 10 years now. I ve been checked by two different cardiologists and a neurologist and no one can tell me what is wrong. What ever it is it seems to be getting worse. It feels like my heart stops for a slit second and I lose control of all body functions except for my brain. As recently as last week I felt it and collasped while walking through Boscov s. I know that there is something seriously wrong I just don t know what. If you ve ever driven over a hill really fast and get that weightless feeling like you re in an elevator that s the feeling I get over and over. Like I stated earlier this has been going on for over ten years and it has become a lot more frequent. If there is anyone that has any idea of what this might be please help. Sincerely, Desperate for answers

### output:

Dizziness has different meanings for different people, but from what I understand from your description of these feeling it seems like lightheadedness. Lightheadedness causes are many, but the most common ones are heart conditions like an arrhythmia, anemia, low blood sugar, postural hypotension, deny Chat Doctor.  As you said the cardiologists have excluded heart disease, but I would suggest having also a rhythm holder and blood pressure holder. These two examinations lasts 24 hours to 7 days, checking the parameters i mentioned above. You should have a blood study regarding cell counting and also blood sugar and hepatic and renal functioning tests. Vertebrobasilar insufficiency can present with dizziness (vertigo, balance impairment or headdress) and also weakness in the legs when it progresses, to diagnose this condition you should undergo an MRA. Sometimes lightheadedness is caused by stress or anxiety.  Also, this symptom is common in people that play wind instruments. I would suggest to 