Can marine collagen contain large amounts of nickel?

Collagen is a protein, and marine collagen (Marine Collagen) is a protein obtained from the skin of sea fish. The manufacturer of the preparation, the photo of which you posted, does not provide information about the presence of nickel in it. All ingredients declared by the manufacturer are indicated on the label. You did not specify the brand of the preparation, but the composition and content of marine collagen Collagen HM™ indicates that it is purified hydrolyzed marine collagen of the French brand Copalis. In the description of this product you can find information that "Copalis® marine collagen is free from GMOs, pesticides, heavy metals and microbial contaminants". However, since it is a dietary supplement and not a medicinal product, it is difficult to verify these statements: https://www.gdziepolek.pl/artykuly/czym-roznia-sie-leki-od-suplementow If the appearance of ailments is clearly associated with the start of taking this product, I suggest discontinuing it and see if they will disappear. This is all the more advisable because breathing problems are potentially life-threatening. Regardless, consider contacting your doctor, you may need some pharmacological support or medical attention. It is also possible that it is some compound or extract mentioned in the composition (and not nickel) that causes your symptoms - it is possible that it is about fish collagen itself. People who are allergic to fish may have an allergic reaction after its consumption. Although the purification of collagen and its fragmentation reduces the risk, an individual reaction cannot be completely excluded. Perhaps this is an allergy that you did not know about so far. I enclose additional information: https://www.gdziepolek.pl/artykuly/jak-i-dlaczego-zglaszac-dzialania-niepozadane