Amoxicillin reaction

I was prescribed amoxicillin just in case an infection occurred and ever since I started taking it I’ve had chest pain. It feels like something is sitting on my chest it comes and goes but it hurts and is scaring me. Has anyone ever had a reaction like this? I was in the ER earlier and they did an ekg, chest x ray, and blood work and couldn’t find anything. It’s not going away