Possible bugs or nute problem?

Can anyone tell me what could have caused this. I went away for 4 days and when I came back this is what I had. It looks a little like the start of overnuting. I want to make sure this is not pest related. For now I will flush and back off on the nutes. P[attachment=o285650][attachment=o285651][attachment=o285652][attachment=o285653]lease help!

I am thinking now it could be wind burn from my 12inch osc. fan. It may be too big for 5x5 tent. What do you all think?