What Causes Pain In Breast And Saggy Breast After Breast Feeding?

I am a 20 year old female mom with a soon-to-be two year old. I breastfeed my son for 6 months and now suffer with super deflated saggy breasts, I look horrible in tops & dresses and I am forced to wear 2 bras to make it look like something. The past week I have been experiencing sharp quick pain in my left breast, and tummy. My veins in my arms are prominent & visible to the eye, I don't have much of a appetite and I sweat a lot lately. What could be the problem?