You're feeling what's very loosely called DOMS, or delayed onset muscle soreness.
The best treatment is prevention. You can avoid a great deal of that soreness by very thorough stretching prior to lifting.
You can prove the accuracy of this by looking at your own experience. Have your biceps ever felt as sore a day or two after a workout as your legs do now? Even nearly as sore? Probably not I'm guessing. The biceps remain closer to full stretch all the time than the quad group and hamstrings. More stretching equals substantially less DOMS.