I feel really dizzy and sick after eating Sardines?

Quite a funny question, however I'm not laughing, I don't know whats causing me to feel to sick. I had a small can this morning on toast. Thought I would be healthy rather than eating a fry up. However like I said, feel 'very' sick. I have not eaten sardines for at least 6 yrs ? Just trying to be healthy lately...but man, I wanna puke. What can I do to help the sicky-ness ?