Hello and welcome. Please do not hesitate to ask follow up questions. Zinc, collagen (that comes from protein), vit C, and also antioxidants like vit E are involved in proper wound healing. I would consider this as a cuase of her symptoms if she is on a restricted diet. Take a look at http://www.pilonidal.org/aftercare/vitamins_diet.htm
However, easy bruising and poor healing are suspicious for blood abnormalities. For example vonWiliibrands disease is a common one that can cause easy bruising.bleeding and affects wound healing. It does tend to run in families. I would recommend that her doc order a complete blood count with differential (CBC with diff) to look at the amount of her different types of blood cells. This test would also be good for evaluating for anemia and blood cancers that can also produce these types of symptoms. Also get bleeding times and coagulations studies (PT, PTT, and INR). This can give insight into the easy bruising as well. Also get blood sugars checked, diabetes impars wound healing--she is young, this would be more likely if you guys have a family history or she is overweight. Certain medications can cause these symptoms as well.
This is a good place to start. I do hope I have helped. It has been a pleasure assisting you. I wish you all the best. Is there anything else I can do for you?