Damn, I think this happened to me too. I got back from Mexico a few weeks ago on a Monday night around 8pm. We ordered Chinese from one of our favorite spots in the city and one that's very reputable. I woke up Tuesday morning (10/23/18) feeling fine and went for a LM session for two hours. I surfed just out from pink house at mid-beach. I came back and ate lunch then immediately felt super tired. I wasn't sure if it was from surfing or I was gassed from being in Mexico. I went down for a nap then woke up an hour later throwing up. That lasted until nighttime and then the next day I was floored and rushing to the toilet every few hours.

My girl didn't surf with me but said her stomach was a little messed up so we figured it was from the Chinese food....however, we've eaten there 10+ times without ever getting sick. We figured it was late Monday night so the food that had sat out too long. Anyway, with your point it very well could have been from that water at LM. Hard to say but it appears that other people in this post have had similar experiences.