Forgive me if I am repeating anyone, I did a search for 'ent' through the posts and found nothing mentioning this.
When you initially enter into the clouds where are your eyes, what are you looking at?
Assuming your eyes are outside or you are at least scanning the outside:
Typically it can be very disorienting entering and exiting IMC, entry being the worst of the 2. If you read around you will here talk of pilots at low altitudes popping in and out say to keep your eyes on the instruments. The reason being is when you look outside and all of the sudden its like someone shuts the closet door, especially at night, it is disorienting.
Instead of looking outside till you enter the clouds try moving to your instruments and keeping there. Don't scan the outside at first, when you first enter your likely nervous especially now since you think you will be sick each time. That nervousness alone can make you nauseous without the clouds so just sit comfortably, keep your head down and still with your eyes on the instruments. Once in IMC for a couple minutes, feeling comfortable, having your nerves, and hopefully not feeling sick. Then you can scan the outside as well.
Seen flyboys? That spinning on a chair with your head down and trying to run a line can help more than you might think. Use a bat for more practical purposes of not need a partner laughing at you. Go up and do unusual attitudes under the hood in an aerobatic aircraft with inverted recoveries.
This stuff will simply make your head and your stomach more comfortable with the sensations of the flying environment. If you can handle the extremes then simple stuff, IMC or not, IMO would be easier.
Good luck with it.
PS I'm not an II but trained in the NE so I had actual many times throughout my training as well as aerobatic work. I feel that stuff helped me a lot though I never had a problem with rides or anything else making me feel nauseous in the first place so.