Sudden, horrific acid reflux - in so much pain . Immediate relief from acid reflux?

I often experience acid reflux, but nothing compared to what I'm experiencing now.

I've taken my medications (progesterone only birth control and antidepressants (sertraline)) in bed before and did it tonight too. Then, out of nowhere, started to get the most horrific acid reflux ever. I am in an ungodly amount of pain.

I've taken gaviscon, I've drunk semi fat milk, I've tried chewing gum and absolutely no relief. I feel like I'm choking. It hurts so freaking bad I don't know what to do.

Please please if anyone has any suggestions to help relieve this asap I would be so grateful.