I don't think you have too much to worry about. Recently I showed up super late two days in a row, but since they were both out of my control (flat tire and car accident blocking the entire road I take to work) my manager was super empathetic and understanding. Explain to your manager that you're genuinely sick, they shouldn't want you working anyway (and if you have a fever you won't pass the covid coach anyway and should be immediately sent home)

I will also add, being marked as "do not rehire" isn't the end of the world. One of my coworkers was flagged as not to rehire (he left his old store on VERY poor terms since he had a super shitty manager) and he simply explained the situation to the manager at our store. She was somehow able to bypass that once she realized why he left

Dude if you’re genuinely sick, don’t even worry about it. There are the types that pull that kinda shit but normally you already expect it of them. If you never portrayed yourself as that kinda worker, you’ll be okay. Bless up homie