Sorry my question is long but i think my kitty has been abused!!?

my kitty Nala (8 months) is usually really friendly with people she follows them around she loves her food goes crazy whenever she knows shes getting fed and is usually very happy. Although the last 3 days (this being day 3) she has gone weird. She has her own room the laundry and there's a little outdoor bit where she can go outside and other cats wont bother her but she usually hangs out in the house with us. Anyway the last 3 days she has hid in a corner outside in a little ball hasnt eaten (which is really weird) and i dont think she has even moved to drink. And whenever i pick her up she gets really scared she lowers her head and goes really still and her claws are out. I had tried many times to sit her infront of her food but she keeps running back to her corner outside. I try and bring her into different rooms with me and just leave her usually shes running around wanting to get pats and exploring but now she huddles in a little ball and as soon as im not looking she runs back outside. Also sometimes when i pick her up she growls and sort of plays dead. Its so weird she just sits there like somthing has scared her stiff. I have come to the conclusion that my housemate and beaten her. I have seen him hit her a couple of times and asked him not to punish her like that but im thinking he didnt listen and im thinking this time he took it too far. This is the only thing i can think of why she being like this but shes even so scared of me HELP what can i do i feel terrible for her i cant take her to the vet im flat broke right now so that is out of the question im just worried about her not eating and if she will snap out of this will she ever be the same again? what can i do?