sounds like its MS related. my very first attack at 18 was a dead leg, i literally couldnt move it if i sat down would go to get up. at the time my doctor thought it were viral and that it would go away, and it did in time, noone every thought MS at the time. I'm 27 now though and was diagnosed last month
good luck with it, let me know how it goes with the doctors. a general GP probably wont do much you really need to see your neurologist