It was definitely ovulation.
I'm not a doctor, and I can't diagnose your girlfriend, but I too have extremely bad ovulation pains; when I was in my younger teenage years they would be so excrutiating that I couldn't walk, and one time I blacked out.
I noticed a week or two ago I ovulated for the first time using yasmin in 8 months, and the following week I felt all the side effects I had heard of: crying, irritabiliy, hungry, not hungry, depressed, little interest in anything, no sex drive, suicidal thoughts, wanting to attack anyone in my presence, and moody.
I would not recommend this birth control to anyone. Many people have said that this causes cysts on their ovaries, weight gain (i myself gained 30 lbs, whether due to appetite or water retention, but the pill was the cause considering I was at the same weight for years before starting this pill) and etc.
You can go to the doctor, but I suggest switching brands as soon as possible!
P.S.:
i also noticed that this may be because of daylight savings time. Did she start taking her pill at a different time? I know that I skimped on timing for a good week or two and this could very well be the cause of my own ovulation. Although chances are slim, I know and listen to my body -- I ovulated on yasmin.