Probiotics and parasites causing lightheadedness and brain fog?

Went on vacation to Mexico, came back and had diarrhea for at least 2 weeks. Had trouble eating and eventually I assumed it would be some kind of intestinal parasite. Looked up and found a paradida complete cleanse on amazon and began taking it. On the second dose I became really sick, felt like I was going to die. My heart was beating fast, couldn't breathe properly, stomach pain and a bunch of stuff. Stopped taking that and I was fine after a couple days. Now, I began taking probiotics around 4 days ago. I became light headed and sensitive to light and brain fog. It feels like I'm in a dream. I feel even worse at nights. I have no appetite at all and I have been losing weight. I am very worried about the brain fog and light headedness so I went to urgent care. They had no idea what it could be and simply told me to take a stool test. I have taken the stool test years ago and it always came back negative (not sure how accurate they are). Does this sound like a parasitic infection, or something else. I worry very easily and the light headedness and brain fog worry me a lot. Is this possibly from the probiotics? Or maybe from the infection itself. Either way, I do not feel normal and I stopped the probiotics more than 24 hours ago. Is this a normal side effect of something or could it be unrelated?