it sounds like a panic attack... u should speak to a neurologist in order to rule out something neurological and then go se a psychiatrist... i wouldn't worry, the most likely cause is a panic attack :)
Does it happen when you are stressed or anxious, sounds like it could be anxiety, i suffered from it for years. Your gp could refer you to mental health for an assesment
Could it be hypoglycemia or low blood sugar? When do these episodes come on? With hypoglycemia you can feel the following symptoms:
nausea
weakness
shakiness
paleness
Hypoglycemia occurs when the blood sugar concentrations fall below a level necessary to properly support the body's need for energy and stability throughout its cells.
For me, my hypoglycemia was so severe I'd pass out. I had this for years, since I was a teenager, and finally got diagnosed with hypothyroidism over 30 years later. The hypothyroidism was the cause of my low blood sugar.
Before I got diagnosed, I had to eat every two to three hours or feel as if I would pass out. The symptoms worsened when my hypothyroidism worsened.