Medicine & pregnancy ?

I had a fever a week ago and I took two alka seltzer.

Like a minute after I took it I started feeling this sharp pain in my uterus but it went away after few minutes. It was very strong I had some tears. Next day I felt a lower back pain for approximately 5 minutes also very strong and ever since I been feeling like there’s something going on in my uterus. I don’t know if I’m pregnant. I took a pregnancy test Tuesday and it was negative maybe it was too soon but I’ll wait a little longer to take another test.

My husband and I don’t want another baby at the moment because we’re moving out of state.

My question is: Is Alka Seltzer bad for pregnancy?