How do you know

When you’re having contractions because I’ve in pain since s Monday and they keep saying is to much acid in my stomach but I genuinely didn’t eat anything that would make me like that is anything the pill they gave me it actually gave me more acidity in m stomach and since yesterday Tuesday I be having pain in my belly button literally feeling pain like I can’t breath of think straight and then it goes away first time for me and im so confused no one explains me how everything is going to happen like I feel like is going to be a surprise 😂😂like people please explain me how am I gonna know