Curious

Can acid reflux or GERD makes you feel nausea and dizziness? I've been experiencing for almost 3 weeks already though I always take omeprazole every morning.

Yes, it can. You’ll want to mention that to the doctor.It could be that the PPI is losing potency, and you may need to switch it. This may indicate that the GERD is no longer well controlled. 

Yes it can . 

I'm pretty sure it can. Nausea - definitely, but i've been trying to link my dizziness with reflux for so long and i actually found a topic on this site where someone wrote about the connection between dizziness and GERD. You can find it if you want to, or i can send it to you or something.

Also what kind of dizziness are you experiencing? When people say they're feeling dizzy it can mean that they're having vertigo or that they feel like they will fall, or that they feel disoriented etc.

Have you tried linking dizziness to the medication though? A lot of medications can cause various side effects - one of them being dizziness. I've personally never taken medication for GERD (unless you'd count sodium bicarbonate as an antacid a medication for GERD) so i don't know much about that aspect, but you should still consider it.

Did you have dizziness before you started medication too?