Hi, I understand your concern. Since, you have already been diagnosed with lactose intolerance, you must be aware of the more common symptoms of the condition such as abdominal bloating, cramps, flatulence and diarrhea upon consumption of dairy products. Bruising is generally not associated with this condition. Can you please describe the bruising , in terms of color and size, that you get every time you consume dairy. Is there any associated itching? How long does it last and when does it go away? Also, try to keep a log book and note down whenever it appears and what food you consumed at that time. It could be a type of allergy.