feeding/pumping pain

So I'm having nipple pain when I feed my baby and when I'm pumping. I have flat nipples so I started off using a nipple shield.. not much pain at first. I tried pumping. it hurt so bad I was in tears. So I avoided that for a bit. I was told that I really need to try not to use the shield for several reasons. I can sometimes get her to latch. it waa still painful. But I could handle it.. But I need to start pumping. i found that using Crisco before I pump makes it bearable. But now when I go to breastfeed..even with the nipple shield I'm in tear pain again. especially at first......does anyone have any helpful advice for me? I have checked the inside of her mouth. And do not see any signs of thrush