Reddit, what should I do?

For the past few weeks, my mom has been experiencing a sharp pain in the left side of her chest and arm. She went to the doctor and they said she was fine, that there's nothing wrong with her. She looked fine for the past few days, but suddenly, she started crying and saying "It hurts" while holding her left arm. I don't know what to do at this point. She's 40 years old and I'm 14. I want the best for her, even if it means I have to get her in the car and illegally drive her to the hospital. Help, Reddit, what should I do about it?

Edit: She just passed out from the pain, now calling an ambulance.

Edit 2: She demanded to go back home saying nothing was wrong. After a ride back, she went back to her room and went to sleep. She got up later and went to a party.