Relax and look at her facial expression when you press on her tummy. She might be in pain somewhere. Or she might also be teething that’s why it hurts to drink milk. Massage her tummy and try giving her milk with a straw if she can use the straw already. Or cup-feed her. Sometimes my LO also drinks lesser milk and I don’t force it on her cause she’s eating solids quite well. At this age, their main nutrients come from their food, not so much from milk.
take it easy mom. Try putting some oil on tummy and massage it. Sometimes babies get like that if they have an upset stomach or colic.