They could have something going on in addition to the molting, but it's my understanding that molting can be a very miserable time for your bird; some will experience these symptoms that you're describing without anything else being 'wrong' with them. To help them regrow their feathers faster, you can increase their protein intake by offering high protein treats instead of fruits/vegetables for awhile. Things like hamburger, canned fish, crushed dry cat food (or thoroughly moistened until soggy dry cat food), canned cat food are high on the list of easily obtained, reasonably priced treats that will help boost their protein & amino acids that are good for feather growth. Rice and peas are also good for amino acids, but reduce their overall protein intake, so if you opt for these, limit portions.