Not feeling myself

Hello everyone, I had my daughter two years ago, I stopped BC as soon as I found out I was pregnant (two years ago) so ever since then, I was taking a BC for breastfeeding moms, nothing that hurt the baby, so after I had her, I didn’t think about switching back, until recently. I just started my second or third pack of birth control, now before I started the doctor told me I had a higher chance to get pregnant. But now since it’s been at least a month on the pill, I had diarrhea today, I have been nauseous and hot and dizzy. I haven’t been feeling right today, I don’t think it’s a virus or anything. But I can’t hold anything down, it goes straight through me. My tummy and heads been hurting. I can’t stop using the bathroom, and I’m not hungry. Could this be the pill making me do all of this or is it something else? I’m scared to be pregnant again. I’m married with a 2 year old, so my husband and I always have sex. I’m worrying myself and don’t know what to do. Thanks in advance!