1 Year Old Suffering From Dry And Hard Stool After Taking Cow Milk. Is It Because Of Cow Milk ?

baby is doing hard pooh, small and dry stools, cries a lot...pls help my 1 year old baby girl doing hard stool poo. 2 weeks ago i stared whole cow milk..after that she feels difficulty nd much crying in doing poo..i am giving her lactolose medicine twice a day.....i am also giving her water nd orange nd prune juice with adding water...but did not work....she is also taking solid food like fruit cereal, fresh fruit like apple, pear, boiled rice nd vegetables...but now a dayes she is not feeling well nd not taking proper food...plz help..what should i do.... may i change her milk.