Unisom withdrawal

I’m 15 weeks pregnant and started taking unisom at around 8 weeks to help cope with morning sickness. I’ve tried several times to stop taking it to see if I’m in the clear for nausea. Day 1 I feel totally fine. Day 2, migraines and vomiting, barely able to eat anything. This has happened 3-4 times that I’ve tried to get off of it. Has anyone else experienced this? After spending the day feeling like I had the flu, I’m going to take half of a unisom and see how I feel tomorrow.