Doxylamine/pyridoxine (Xonvea™, Cariban™)
This is the only licensed drug treatment for nausea and vomiting of pregnancy. It contains a combination of the antihistamine doxylamine and the vitamin pyridoxine. It became available in England in 2018. It has been widely used for pregnancy sickness in the US and Canada and studies have shown no link with birth defects in the baby. The antihistamine doxylamine might be more likely to cause drowsiness in nursling. https://www.ncbi.nlm.nih.gov/books/NBK500620/ and https://www.e-lactancia.org/breastfeeding/doxylamine-succinate/product/. The 10mg of pyridoxine is unlikely to cause any disruption to breastfeed.
See also Vomiting in pregnancy whilst still breastfeeding – Breastfeeding and Medication