You need to see a doctor to rule out any physical causes. Try and keep track of when and where these episodes occur. Keep a journal of your moods, the food you ate and any activities to see if there's a pattern. Then discuss them with your Dr. If you don't have insurance you can find a clinic or teaching hospitol to go to in your area.
Good Luck, I suffer from panic and know how helpless it feels
Weakness with feelings of light headedness can be from anaemia (low iron levels in your body.
If you have not been eating the right foods or dieting, your iron levels may be too low. Iron is required to build the red corpuscles that carry oxygen around our bodies. Iron rich foods are liver, kidneys, dark greens, cereals are fortified with iron and folic acid (this helps the absorption of iron).
You should make an appointment with your doctor to do a blood test to see if you are anaemic or if there is any other problem like high or low blood pressure, inner ear infections, etc.
Make sure that you drink enough water throughout the day.
do you breath really heavy and sweat when this happens.it could be blood pressure related or very bad panic attacks (which dont have to have logical triggers). id go see your doc though