My lips and tongue feel numb?

For the last 6 weeks my lips have felt numb, now my tongue has started to feel numb aswell. It seems to be worse within a short time of eating. I have tried to eliminate different foods, but i can't seem to pinpoint anything in particular. I ate a packet of crisp the other night and my lips and tongue felt numb within minutes. My arms usually start to feel itchy at the same time, i dont know if this is a connection.