Saw dentist yesterday & was told my pain was from an abscess. Its on my lower left side. Gave me amox and we are waiting for approval from ins for a root canal. My face is swollen and numb between my lip and chin today. Should I go back asap or wait?

Go Back ASAP. The pressure and toxins from the abscess are affecting the inferior alveolar nerve. That tooth needs to be opened and drained ASAP, insurance or no insurance. Emergencies cannot wait for ins approval, so get necessary treatment started now before the infection spreads or causes permanent damage.