D.B.
I wouldn't fool around with this - dehydration (from vomiting, diarrhea and not eating/drinking) is serious, and what can happen is that your blood sugar level drops so low that it results in more nausea. So it's a vicious cycle.
At 24 weeks, you should be well past the morning sickness thing, and that doesn't come with diarrhea anyway. And I am sure you would have mentioned it if you'd be nauseated all along.
I don't know whether you have a virus or intestinal bug - some of those can last a while. However, I'm kind of shocked that your doctor just gave you medicine to take (how does one keep it down if one is throwing up all the time?) and didn't follow up. Did you stop the medicine because it didn't work at all? You said "nothing happens" so you stopped after 4 days, but then you say everything has come back, so maybe the medicine was doing something? Hard to know without knowing what you took.
It's ridiculous to be 24 weeks pregnant and not have your doctor be more concerned. Did you call the doctor at the 4 day point or the 7 day point? Or does the doctor not know this? You went off the iron (makes sense - that can upset the stomach) but then you stopped the other meds and went back on the iron. Did you update the doctor on this? Don't mess around with starting/stopping medications while pregnant without consulting your doctor.
Regardless, if you cannot get through to your OB/GYN immediately and update him/her on this situation, or if you have talked to the doctor through this and don't trust him/her, I really think you need to go to Urgent Care or perhaps even the ER and get some IV fluids (bypassing your stomach so you won't get sick). Don't drive - have someone take you.
When you get through this crisis, please find a doctor you can confide in and trust.