Is it nausea or acid reflux?

So ill be 6 weeks on saturday. The last few weeks ive had that knotty, about to vomit feeling in my throat. Most of the time when i burp a bit of vomit comes up but i dont have any heart burn. I take my prenatal at night as i read it helps prevent morning sickness and so far its worked. No morning sickness at all. So is the burp/vomit taking place of morning sickness or have a developed acid reflux? 1st time making it this far in a pregnancy so i dont know.