Not sure - maybe you could email some manufacturers of the better fish oil products out there (ie, those with the fewest contaminants)? Or talk to a good nutritionist or allergist?

I googled "fish oil shellfish allergy" and found some links with different views on this issue - some sources suggest that taking fish oil supplements might be OK in your situation. But I'm by no means an expert - you should definitely get properly informed before deciding to go down this road.