What could this be?

Since last night I’ve been feeling like I’m really down. I sometimes want to cry but I don’t know why. And today I’m just feeling useless I feel like trash. I work in a hospital as a cna in the post partum unit and my position here is fairly new but I feel like I’m just scum and not needed. It’s never the nurses, they make me feel very important. But I know the reality, I’m not vital and I just feel like I don’t belong here since everyone has such an important role and here I am, changing linen. It might just be something hormonal like my period coming up but I definitely don’t great. Sorry to rant, I didn’t know who else to talk too, I don’t have friends so just wanted to be heard I guess.