Sick but don’t know cause

Em

So I have 2 days until my fertile window. Had a full period, little bit of cramping still . I have felt nauseous the past 2 days, even when I wake up and it’s all day long and gets worse in the heat. Had stomach issues but when I puke, it’s not really puke. It doesn’t have texture and it’s literally just liquid. After I eat I need to puke or something it feels like I have to use the bathroom..any ideas? Of what it is, or how to fix it?