Some dogs shed a lot, you could try a daily fish oil supplement…in case the shedding is related to dry skin.
She may have environmental allergies, if so, and it is causing her discomfort for 4 seasons, I would consider getting her tested. http://www.allergydogcentral.com/2011/06/30/dog-allergy-testing-and-allergy-shots/#comment-1283
Have you considered a home made diet? You could still use kibble as a base
http://www.homeovet.net/dynamic/php/downloads/dog-c8470f2c75dbe4b683205c3919ee2310/dog_diet_complete.pdf
Is she getting enough exercise? A 20 minute brisk walk 2 or 3 times a day will aid with weight loss.
