Could it be in the grip you're using, either being too wide or too narrow? If your now lifting heavier weight after training 2 years (heavy, relative to you) in such a way that your hand is not plumb or perpendicular to your forearm, that puts more stress on the joint. It doesn't take much of that to begin to experience some of what you're describing.
If that doesn't work, try an e-z curl bar, or if that's what you're using, switch to a straight bar. And if both of those bother you, stick with the dumbells for awhile until they're healed. When you switch back to barbell ease into it.