Judging by the reaction your body experienced there's a strong possibility you're allergic to the fish oil. There may be salmon proteins in the fish oil which may have caused your allergic reaction.

A possible alternative for people who are allergic to fish is neptune krill oil. A study comparing fish oil and neptune krill oil found the krill oil lowered cholesterol and triglyceride levels more effectively. You can see the results of this study right here.

Neptune krill oil may cost a bit more than fish oils, but I think the price may be similar to buying a pharmaceutical-grade fish oil with high concentrations of omega 3 fatty acids (greater than 80%). Good luck and I hope this information is helpful.