I need advice.. please

I have never felt this level of stomach pain so quickly. I ate egg salad for breakfast.. normal breakfast for me lately. Out of no where I got instant stomach pains and I threw up. I had to lay on the floor. the pain is still there but I dont have the urge to throw up anymore.

3 days late all test negative. I'm confused. has anyone else gone through this and gotten a positive later on?

I have been using these pregnancy test strips I got from Walmart and read that the Walmart ones are known for giving negatives. is there any truth in that?

any advice or experiences is appreciated.

thank you

ashley