Verizon terminated me while I was extending my disability claim, what can I do?

Verizon terminated my employment in the middle of me filing and extension for my Short term disability, Verizon knew I was still injured and doing everything my doctors and specialist were requiring me to get better, it was just taking longer than initially anticipated because of scheduling appts/etc, so I filed for an extension about 10 days before the original claim was ending and even the claim company Sedgwick gave me a few weeks to get the doctors notes and upcoming appt documentation, so about 3 days after the original claim ended I get a call from my boss's boss and HR rep telling me I'm terminated even though they both knew my claim was being extended, and I actually got notice later that afternoon that it was approved, but I was already terminated according to Verizon, what should I do? I have no medical insurance anymore through Verizon and I need surgery on my spine.