Try benedryl. Really.
I am a 6 time HG survivor. Mine was so severe though that I literally didn't leave my bed for 3 month during 4 pregnancies. I slept 22 hours a day and vomited the other 2.
A zofran pump may help as well. There is also a wrist band device that is FDA approved for HG. I am trying to remember the name but There are success stories on the helpher.org website. Some great tips there as well.
Katie, mom to Olivia (97), Veda (98), Franky (2004), Wendy (2005), JoHannah (2007), Thea (2009) and Sunny (2011)