Red meat intolerance?

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I ate about a 4oz portion of flank steak last night and almost immediately felt sick after my meal. I thought maybe it was because it was a larger meal than I've been eating but it was still pretty small. Veggies, a small potato, beans and a little steak.

We don't eat a lot of red meat. Maybe once or twice a month. My boyfriend will insist I eat a little because I've always had low iron. and take supplements. I get my protein from beans, nuts, white meats, etc.

Tried to shake it off and went to the gym 2 1/2 hours later by the end of my workout I felt even worse. I had to go home and lay down.

Does anyone else get this way? Is it normal? What have you done to correct it?