Fell sick after being served off food

We had dinner at John Dory's Secunda last night. I ordered the Hake Thermidor (Hake fillet covered with cheesy prawn and mushroom sauce topped with mussels) It wasn't great and the mussels were under cooked. I did not think much of it at the time and I just wanted to finish my meal and get home. I woke up in the morning hours with a cold fever and terrible stomach cramps, thought I was going to die. We used to love John Dory's but after this experience I will never ever eat at a John Dory's again