Deadly shoes

Purchased sandals from Mr price on Saturday , to wear in Sunday when I did they were so painful I thought maybe I needed to break them in, decided to not continue with the shoes and wore a different pair. Monday wore the same sandals to work, the pain was so excruciating by the time I came home my feet were swollen and itchy like in have foot fungus. Woke up this morning (Tuesday) and my feet are still sore and swollen , I feel so defeated, I actually want to go see a Dr for this as there is something in their shoe material that is deadly. The funny thing is this is not the first time this has happened to me with their shoes, and no I don't but small make I buy my size or even size up if it's a small make but I had the same issue with their sandals before. I thought of wanting to return the shoes but I know they won't accept them as they have been worn. Wasted my money and almost caused me health issues.