Appraisals came in WAAAAY too low? Options?

[Jeff Plotkin]

I went for my first two BRRRR deals at the same time this summer and everything went great. I got tenants in both properties and they turned out beautifully. Both homes were purchased and rehabbed with cash. Today, I got the appraisals back for both properties (doing both BRRRRs as two separate loans from the same lender) and they came back insanely low. The house next door to one of them sold for $165k but mine appraised for $123k, and the other house was even lower.

What should I do? Can I ask for a second appraisal? Should I try waiting a few months and go with a different lender? I can't accept these loan terms at these appraised values.