Anak, please see your doctor or go to the hospital right away, hindi yan normal heartburn lang, at 31 weeks kailangan ng proper check-up agad. Those symptoms together (difficulty breathing, cold sweats, nausea, dizziness) need medical attention immediately, hindi pwedeng hintayan.
Alam ko it's scary, pero mas safe kung makita ng doctor kaagad para ma-rule out anything serious. Wishing you well, mama!