i had similar problems with summer but not quite as bad, she would seem hungry all the time so i would feed her then she would be sick then not long after she would be crying as she was hungry again. My health visitor told me it was because i was over feeding her, and thats why she was sicking loads of it bk up. i know how hard it is not too feed her as much when she is now used to getting fed as this is what happened with summer. so i changed her to the hungry baby milk, i was not told to do so by my health visitor but did it anyway as it seemed the only logical answer and its worked great, it took her a little while after changing it to get into a rountine now in the day she is fed every 3 hours has her last bottle about 10ish and sleeps through the night no problems, sometimes until 9.00am the next morning.
hope things get better, but its worth a thought, i do know tht changing the milk does not suit everybaby tho!