Contamination as in something getting into the tank that shouldn't be in there, and that could have an effect on the fish. I have no idea what the ingredients are in that cream and I'm not a chemist or biologist either, so I cannot tell you whether it's likely to affect or kill your fish I'm afraid, but anything like perfumes/creams/moisturiser/air freshener contaminating the water has the potential to contain something that could harm the fish. A friend of mine lost most of her stock from her 55g tank when her little boy put his fingers in the tank to play with the fish after they'd been out and used hand sanitiser on his hands. Complete accident, very small amount of the product diluted into a large tank, but it caused bleeding in the brain and killed most of her fish.
Do you usually do water changes? Because if it's not typical for you to do large-ish water changes often, then large water changes can be dangerous too. No judgement either way, promise, just want to see what a typical water change routine is in order to know the best next steps. When was the last time they had a water change? If it's been a while or infequent, then smaller, staggered changes might be needed. If the fish get worse though, then we'd have to consider risking large changes anyhow... it's a tricky situation, but yes, it's a real risk.