4 year old Hen with feather and weight issues

Hi, my oldest chicken is concerning me a little. About a month ago I noticed that her fluff feathers had not lost the sheathing around them. I brought her in, gave her a bath and helped remove the sheathing. Now they are all fluffy and look good (I will add that she did not have about 75% of these feathers before due to a lice problem over a year ago so I am happy to see that her little bum is covered!).

However, the rest of her is not looking so great. She looks like she started to molt but then had second thoughts about it. Many feathers look broken, her tail feathers are ratty, but what new feathers she did grow are shiny and full. What would cause this? I also think she has lost some weight. I will weigh her tomorrow so I have a frame of reference.

I wormed her with Safeguard today. She is eating, drinking, laying regularly, and still rules the roost. When I brought her in to bath her I feed her some rice with buttermilk and coconut oil for a week.

I was feeding Feather Fixer for a few months when everyone was molting and I had a very happy flock. Then I switched back to Ranchway's organic no corn no soy and the girls were not happy. So I switched to Nature Smart organic and they were still squawking at me like they were hungry (the have free choice feed) so I mixed in Nutrena's All Flock for more protein. It is a good size pellet, could that be a problem for this hen? She also gets BOSS as a treat.

Just this afternoon after I wormed her I made a little mash for her, she ate a little and then wandered around the yard and started eating any little patch of grass that was peeking through the snow. We have had some heavy snow and cold temps lately, I have never given my chickens scratch but I am thinking of picking up a bag tomorrow.

Any ideas or recommendations for caring for the aging chicken? Thanks!

Here are a few shots of some of the broken feathers under her wings.