leg pain

This is my second pregnancy, my first born 6/22/2011, I am 24weeks duethe 1st of june. This preg my legs hurt bad, sharp pains can bend for more then couple min. Standing for too long is unbearable. I work as a clerk at quik trip ( a gas station) so I stand at work without sitting breaks just kinda rest here and there. They seem to go to sleep easily and I am just wondering if any of u know if this could be serious?