Hun, I've been where you are. My pregnancy with DD literally almost killed me, my kidneys were struggling and I physically couldn't open my eyes, move, sit up, I often couldn't muster anything to move from the toilet once I threw up, I stayed there for 9 hours until DH found me after work :-( I took leave for the entire pregnancy. My second pregnancy was similar but I medicated far earlier. The nausea was always there but the vomiting became less severe, with maybe 6 times a day by 20 weeks.

I don't want to alarm you, but my doctor suggested Restavit when I had bad morning sickness and the pharmacist asked me what I wanted it for. When I mentioned morning sickeness he almost fell over. He said I should definitely not take it whilst pregnant.
Restavit is prescribed regularly for women with HG it can have great effects. I have never used it though.

If your head is aching, you are obviously dehydrated. I don't want to be pushy but if you can get some IV fluid into you in the ED or even the Dr's surgery it will help in getting to a 'base line' for your body.

Zofran can ease vomiting and nausea (more vomiting) but it needs to be started before your brain over rides its ability to work. It may never stop the vomiting but it 'should' alleviate it to a certain degree. Its job is to push the contents of your stomach into your bowel in an attempt to stop you spewing. Yes, there is nothing there but it can help take the edge of the nausea too. If only slightly so you can move. If you do not start the medication early enough you will be unlikely to get it to override the brains ability to stop throwing up.

Taking Zofran at the same time each day ALL the time seems to have more effect than taking it as you feel sick. Depending on your dose rate as to how you can take it. With DS I was on 3 x 8mg/ day, I took it for the entire duration and was sick until 2 days after birth. DD (my first baby) eased at 38.5 weeks but I stopped medication at 20 weeks because I was sick of paying money and throwing up 12 times a day still.

I hope it eases for you soon. It can be very traumatic and lonely

ETA: I think it may be an idea to consider that it is in fact HG and not bad morning sickness. They are two VERY different things