What Causes Numbness In Arms And Legs?

I have been experiencing a really weird feeling which is very hard to explain. I keep getting sometimes slight numbness in either arm or either leg, slight shortness of breathing, twitches of very slight pain feeling as if it comes from my veins/bloodstream, I wouldn t call it pain but I can t describe it in any other way, headaches, I find it s usually on one side of the body but that changes, sometimes both sides, I would go to a GP but I don t think they would be able to help me because I can t really explain very well what it is. I keep getting paranoid that is may be early signs of stroke or heart attack but I know the chances of that are very slim especially as I am only 16 and don t have any obvious health problems. Thanks