If it is a new bike, you should take it to the shop where you bought it and have it adjusted properly.

However, in case that is not possible for some reason:

Your head set probably needs adjusting. Can you show what the headset near the top below the stem looks like (where the handlebar connects). There are a couple of different types that adjust differently.

By the way, if it is what I suspect, you should also see some movement near the stem when you lift up also. If not, I am lost.

EDIT: I just reread your first message... What is "flipped my stem?" Did you have an accident?