I traveled to Costa Rica in January. About a month later, I had 3 episodes of "seizing" constipation, and ever since have had daily bloating and intestinal gas, especially after meals, along with periodic constipation. Two of the four stool samples I provided my doctor have come back negative. (Last two have not yet come back.) However, in each of the samples, taken on three different days, small white seed-like bits (size of a sesame seed - which I do not eat) were clearly visible. Parasites? Are the other likely culprits? Thank you.