Family issues😖

Okay, well I don't know what topic to post this in, so I just went with 'teen talk'. So, recently my mum has been really ill( not like a sickness, more like a mental illness, we don't know what yet!) and has been sleeping for most of the day(s)! She hadn't been eating, socialising or herself for about 2-3 weeks and I'm starting to get worried! My step-dad hasn't helped as he's causing my mum to cry/ become upset! He is helping around the house, but make mine and my mums life's a living hell! He's not at all abuseive, but he does say stuff that make me cry, a lot! It's been like this for too long, and I will admit sometimes I can be a bitch, but I would NEVER hurt or upset my mum in anyway!!! I just need some advice on how to help my mum and advice on how to sort the issue with my step-dad!