I've been taking doxycycline to treat chlamydia and i've vomited several times after 30-45 minutes of taking it, am i still being treated?

Probably yes...: Apparently, you got gi-upset as its side effect; but a duration of 3-45 minutes should be enough for absorption for most of oral drugs. Did you see the remnant of pills in the vomitus? Meanwhile, the pace of possible clinical resolution of chlamydia-related symptoms may help tell the story. But for worse, it's always possible to try other drugs with less side effects as needed. Work with doctor...