Help!

In desperate need of some advise from other mums. My little boy is 12 weeks old today and is currently having 7oz bottles of extra hungry baby milk 4 times a day but only drinks 5-6oz most of the time. He sleeps from 8pm till 7-8am no problem. But For the last 2 days he has been very fussy and wanting a bottle every hour or 2 at a push. He's cranky and won't nap but still sleeping through the night. He's screaming all day. I suffer from severe depression and don't know how much longer I can be on my own with a constant screaming baby. I know that's par for the course of been a mum but he's always been such a quite baby and this has come completely out of the blue and knocked me for six. Any advise would be so so fantasticĀ