I Was Started On Remeron 15mg This Week. Started 1st

I was started on Remeron 15mg this week. Started 1st night on Thursday....went to bed and felt fine however overslept the next morning. Last night (Friday) I took the Remeron at 9:00 p.m. I sat up and read till 10:30 then felt I needed to go to bed. After I was up and out of my chair (2-3 minutes) I suddenly felt as if a whole fifth of alcohol had just hit me....A terrible sense of motion (no vertigo) and instability with gait and was worried I could not get to bed. Managed to crawl to bed and once in bed, gradually felt better. Today, I have felt extremely "spacey". Do you think it could be due to the Remeron? I was also started on at the same time, Flomax. I intend to contact my physician on Monday but wonder if I should try a continue the Remeron??
Thanks