Please someone help! Im soo worried/concerned about my dad ! :(?

okay so my dad has been having really bad chest pains lately, this started about last week or so but at that time it was off and on. yesterday we went to kings dominion and he went on the anaconda with me (bad idea) so after wards he was having really bad heart burn and i was concerned, so then it went away , but kept on comming back. then today we went to the store together and he was carrying 2 bags of groceries and when we got into the car, his chest pains came back and we had to sit in the car for a few minutes, before we could drive off, it was so bad. then when we got home he went straight to bed to lay down and relax, also my mom had to help him get up, when he was laying on his back, it hurt so much. and im Reallyy worried about him! Hes 51 years old, but very healthy!! he eats fruit apples, pears etc.. every single day. he can do those flips on the monkey bars, he can cook, play basketball, soccer, tenis, ride bikes, do bascitly EVERYTHING/Anyhting you can think of. Hes amazing and i love him, but im so concerned about him and his health. why do you think he's having these random chest pains?? He also says that it hurts him to twist and turn, and it feels like something is being squashed in between the center of his chest, behind his breast plate. he says he is breathing fine and his heart feels fine, but ive noticed that he has been walking alittle funny like bending over to walk so the pain doesnt come back. he says that he cant turn his head to look at something, he has to shift his whole body to look at something behind/to the side of him. I am really really worried about him and am wondering what can be done to stop these pains in his chest or help/treat them? Please read because i need answers, before something goes terribly rong. :(