Food Allergies Treatment

when i drink milk i get really bad sharp sharp stomache pains that sometimes feel like iam gunna die and i have to go to the bathroom really bad and i start to also throw up it lasts about an hour and a half but it hurts so bad ..my friends think iam a lieer so i wanted to prove them wrong and now my stomache hurts so bad and iam sweating like crazy and i feel like i have to go to the bathroom really bad and like iam gunna throw up..should i go to the ER??