I would wait until spring to do anything to Begonias unless you have ample light for them. I have a ton of them in the house, but during winter, they are just surviving, not really doing much. That's what they've done in the house the past few years since other plants take precedence over getting the good light spots, but they pop back to life when they can go outside again. I've given up on trying to do cuttings of Begonias over winter since they don't seem to be able to do it well in the conditions I have available for them.
Forgot to say, pale sounds like chlorosis. Could be from nitrogen deficiency, or tap water making the PH of the soil too high.
