Blood Vomiting at Resort - Occidental Punta cana, Punta Cana La Altagracia

Punta Cana, 23000 La Altagracia, Dominican Republic

We were on vacation in the Dominican Republic for about 14 days in August 2019 - Hotel Occidental Punta Cana.
I don't know after how many days it started, I think around the 5th day.
My partner and I were in the ocean, standing in the water and suddenly my boyfriend spit blood.
Just out of thin air.
He told me he wasn't doing so well, but didn't want it to be noticed and didn't say anything before that.
We then went to the hotel doctor and described our problem, but were not really taken seriously. As he panicked due to this incident (including a pre-existing condition with high blood pressure), it got worse. He couldn't sleep anymore and bought sleeping pills.
We are of the opinion that something was also poisoned.
Who else just spits blood like that?! The amount of blood was about a good big handful. No one took us seriously or helped us.
He only felt somewhat better after about 4-5 days. That was just awful!! | Symptoms: Other