Unable to eat

I fumbled on a girl I really liked she was giving me hints and was so nice to me as well but I am always afraid to start flirting and stuff and in a few weeks she lost her interest and I didn't even get a text back in 3-4 days and since then idk I felt a loss of appetite completely, I don't feel like eating at all I didn't eat yesterday, I just had some milk and cornflakes today and skipped lunch and I don't feel like having my dinner as well , I don't feel like getting out of my room I just wanna lock myself in forever , my roommate is good , but i wish I was living in a single room. I know I should eat but I just don't feel like my brain is not signalling me to and I have had really negative thoughts and I feel depressed