Help, my chest's been feeling heavy since i woke up?

Since I woke up this morning, my chest's been feeling heavy, as if it's being stamped on. This hasn't happened to me before. I feel better when I lay down, but worsen if I stand up or bend down. I wonder what's wrong? Last night I ate some MSG food but I've been consuming MSG since a long time. I don't have asthma or cardiac problem. Thanks.