Is it normal to be possibly pregnant from this circumstance?

So my girlfriend got the birth control shot and an iud implanted in her about 3weeks ago. Two weeks ago we had sex with a condom and everything was ok. A week ago we had sex in the hot tub without a condom but I pulled out and ever since then she's been feeling sick. It's been 4days since the hot tub incident and she's still nauseated. Her period is also two days late. The catch is that the iud fell out today when she was watching tv. We've heard that the iud can cause people to get sick and we're quite worried. Could she be pregnant or is this her body getting messed up from the iud? Is this mormal? Please give real answers guys, we're worried. Thanks a lot