Hi
Welcome to the forum!
Is your girlfriend on any medications like anticoagulants, blood thinners or birth control pills. The commonest cause is OCPs or birth control pills. Check with her if she is on any of these. If she is on them she should immediately consult her gynecologist regarding changing the prescription or go for another contraceptive method like the IUD.
The other possible reasons are low platelet count, clotting disorders, fragile spider veins, deep vein thrombus, deficiency of Vitamin B12, folic acid, or Vit K, a liver disease or certain cancers. It could also be due to pressure urticaria.
It is difficult to comment beyond this without examining. A comprehensive investigation is required keeping all the points in mind.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Has she had her prothrombin time tested? How about her adrenal function and ACTH?
still waiting for answers.