Is there a proper way to stop taking this?

I started on B6 and Unisom 3x day on week 8 for my morning sickness. I went down to nighttime only at 12 weeks. I’m 18 weeks now and have had zero nausea for almost a month so I decided to stop taking it altogether. I’m one of those people who doesn’t like taking medications. I stopped it Thursday night. I actually slept OK the last 2 nights but now today (Saturday) my nausea is back full force. I feel like I’m 6 weeks pregnant again. Obviously I started taking it again but am curious if anyone has had a similar experience. I’m not sure if my nausea is a result of taking the medication out of my system or if the morning sickness is still actually there.