I've got a lvl 25 Hunter and I had the same problem around that point. My problem was that I wasn't getting enough hits. There were times that more than 75% of my shots would miss. I am guessing you're having the same problem if you did the same build. The solution: put more points in dex, at least 2 with 3 in luck or if it's really bad put them all in dex for one level (that's what I had to do). After you get back to a reasonable dex you should find that kill come much easier. At level 24, I could kill orange monsters solo with only my own buffs and half of the godesses' blessing. If this still doesn't work, you probably have too many points in str (I only have 20 and it works for me). If this is the case, I suggest starting a new character because it will only get worse from here. I had to abandon my lvl 23 hunter because I focused too much on strength and he couldn't even kill a green.
Hope that helps.