As others said IM H that you get on the street is very risky practice that will eventually cause serious health issues.
Ativan is great for opiate withdrawal if it's intravenous because on the top of standard benzodiazepine effects, it's also an antiemetic. I know people who got through heroin withdrawal very comfortably just with IV Ativan and Clonidine at a hospital.
I agree with others regarding the choice of benzodiazepine. Lorazepam, unless it's IV, seems like a poor choice but definitely better than nothing. I also think that Alprazolam isn't a great choice for a long opiate withdrawal because it's very effective for a very short period of time so you need to dose very often which clinics/ hospitals generally won't let you.
A long acting potent benzodiazepine is the way to go. Clonazepam and Diazepam are good but I would choose Clonazepam because it's as potent as Alprazolam and it has much longer half life. Diazepam is great, especially the very long half life and the effectiveness of muscle relaxant properties but it's not as strong as Clonazepam or Alprazolam. If you could get Clonazepam and as an addition Alprazolam in order to just knock you out, it would be wonderful but seems hard to get.
I'm sure that they will give you Clonidine which will help with most of the symptoms, especially the hot/ cold flashes and not being able to stand still. If they don't give it, definitely ask for it. It will make it much better. They don't have a problem giving it because it's not a narcotic so don't hold yourself back.
Nausea is a big issue which Ondansetron (Zofran) is great for. They have an intravenous preparation as well as the oral one. If you stay at a hospital, ask for the IV. It's much faster and you don't have to worry about vomiting it out.
For RLS, as mentioned earlier, Gabapentin & Pregabalin seem like the best medications. Clonidine and benzodiazepines help it but not really stop it like high dose Gaba/Pregaba.
Hydroxyzine is a good antihistamine that has antiemetic and muscle relaxing effects. It also potentiates all the other depressants that you will use.
Good luck, I hope that you solve this problem.