I'm sorry to see this happen to ya. But I'd be sending her back. Don't fly her no more as it could get worse and then the unthinkable could happen...
I'd say the left hand side hex nut may not have been tightened correctly back at Dji land. Is there much movement in the said area as apposed to the other side?
DO NOT! try and tighten this the hex nut because you will void your warranty. Loose hex nuts were mostly found on version A's. This is why they now supposedly check the nut then apply the warranty sticker onto the nut and boom. I guess this one got away..
Sorry mate but it looks like you'll be waiting for her at least 6 weeks before she's all mended up unless your place of purchase may be nice enough to replace just the bird or the entire kit for you?