Are the cecals just excess ones, but normal grape like clusters, or are they semiformed or unformed mushy cecals?
http://www.medirabbit.com/EN/GI_diseases/drop/Drp_en.htm
If the collard greens are new to her, I would suggest stopping them while you are transitioning onto a new pellet, so that when there are problems like you are currently having, you will only be introducing one new food and will know what is causing the GI upset or change. Did she have the cecal issues before you started changing pellets or did this start happening with the introduction of the new pellets?
The recommended feeding amount of 1/4 cup pellets per 5 lbs. body weight, is just a general guideline on some rabbit sites. A better guideline is 1/4-1/2 cup per 6 lbs. body weight, but again, that is just a guideline. The amount of pellets each rabbit needs depends on the type of pellet being fed as well as the metabolism of your individual rabbit, along with any other foods that are being fed. More or less pellets than the guidelines may be required depending on each individual rabbits needs. You judge the amount by what keeps your rabbit at a healthy weight and also supports healthy GI function. If a rabbit is having excess cecals, then the diet is too rich, from too many pellets and/or too many veggies/treats. The same applies when you are seeing unformed or semiformed cecotropes. Often it is from too many pellets and/or treats, but sometimes it can be caused by a sensitivity to a veggie being fed. When a rabbit is having these issues, you will have to do some experimenting to find the cause. Are you also feeding unlimited hay, and if so what type? The fiber from hay is important for good GI health and can help clear up these kind of problems when the right balance of hay and pellets is found.
You may be transitioning pellets too quickly. If the cecal problems started when you began transitioning, then this could be the cause of it. Usually a transition should take about two weeks, but with some rabbits it needs to be done even slower. So you may need to cut back the amount of new pellets that you are giving and transition onto them more slowly.
There are health issues that can cause fur loss, but more commonly it happens with a bad molt or false pregnancy for unspayed females. Do you know if it is just falling out or if your bun is pulling it out? Are you seeing any signs of skin irritation or does it look healthy?