I already had older children who were weaned at 4-5 months and appear to be fine, so I just introduced solids at 4.5 months with my daughter, which more or less solved the problem. Before this I also put the baby in the car seat after feeds for at least 20 mins which seemed to help her keep something down. One of my older incredibly sicky children practically had to live in his car seat for the first few months - of course we were unaware of the dangers back then so didn't worry so much.