I've finally decided to take vocal lessons the main reason why is this...

I played a 3a hour show tonight, singing throughout all of it and my voice is shot now. I literally cannot speak above a whisper two hours removed from performing. Granted this is the longest show I've ever played but it still doesn't seem normal to me. I have another show Monday night and im worried im going to have to cancel. So next week is going to be dedicated to finding a good vocal coach. However I've heard horror stories about people claiming to be coaches and really not knowing what they're doing so what should I look for in a good guy? What are the signs that tell me to runaway as fast as I can? Also any advice on how to get my voice back by Monday would be greatly appreciated.

Tl:dr what signs can tell me wither a coach is good or bad and how to heal a lost voice asap?

Thanks in advance guys