The young midfielder grabbed the headlines last week after coming off the bench to score two superb goals in our 4-0 win against Stockport County.
He was almost guaranteed a starting place with Oyvind Leonhardsen out for six weeks but disaster struck at the end of last week when he started to suffer from the effects of a virus.
Davies tried to tough it out in the midfield cauldron against Leeds United on Saturday but he was clearly struggling and substituted at half-time. He was immediately pulled out of the Welsh Under-21 squad and has been told to rest at home for the early part of this week.
A devastated Davies revealed: "I've been pretty ill all week and been on antibiotics and to be honest, I've not really recovered and I just didn't have anything in me at all. I felt so weak and couldn't really do my justice.
"I struggled to breathe in the game and I haven't been eating properly, I haven't really had an appetite, so it's all come out.
"It's an absolute nightmare for me but one of those things I suppose. I been pulled out of the Welsh squad and I've been told to stay at home, rest and try to get my energy levels back up."
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Simon Davies quickly crashed down from the biggest high in his football career.