I am reading with my mouth wide open in disbelief at your (lack of) treatment OP.
Obviously your awful pain and constant vomiting is irrelevant as long as the blood result print out hasn't flagged anything bad to them, and out the door with you asap, NEXT!. But there's something wrong and to think that a National Health Emergency department would send you home twice in excruciating pain, unable to keep nutrition down, and all the rest is just, well beyond my comprehension.
I mean what are people supposed to do when they are like this? I hate to say it, but you'd probably get better treatment in a Third World Country.
I think I'd drop down on the floor before their eyes and pretend to faint/pass out and stay that way looking groggy until they did something for me. After two discharges with nothing but pain relief I'd act it out. Well I say that now, but honestly if in so much pain and discomfort I reckon after two failed trips I'd do anything.
I can only wish you the very best and hope you see some improvement when you fill your scripts. I am just so bewildered by your lack of treatment, that it's frightened me in case I ever have to to A+E. Seems like it's heart attack, stroke, major accidents only now. So what do we do? Especially on a weekend. Good luck.