Cycle effected by not your newborn

Natalie

My neighbor had a baby about 3-4days after I ovulated. Due to prior circumstances, she needs help caring for her so I've found myself with a newborn way more than intended lol. 9dpo I've started to feel sick, currently 12 but it's only progressed to all day sickness. I feel like I'm about to start my period, my back hurts, nauseated, and having weird cramps every once in a while similar to lightening crotch but near my ovary. I know time will tell what's going on but I just can't help wondering if somehow the caring for the baby changed my cycle, and that's the reason I'm so nauseated, or if I could be pregnant myself, or maybe this cycle this is my period symptoms as this whole cycle has been slightly different. I may also just be sick lol. So if you've made it this far, thank you for sticking with my ramble, has anyone had caring for a newborn change their cycle/symptoms?