What Causes Tightness And Squeezing Sensation In Forearm?

Asking for a relative, she's in her mid 20s, slender. She's experiencing a tightness or squeezing sensation in her forearms, her skin is turning blue. I've seen pics, almost looks like bruising. Asking which specialist she should go to. The emergency room sent her home, told her to have blood work taken tomorrow, pfft.