I take them and I don't get burps. I never heard of anyone having smelly sweat from taking fish oil. I don't know how they would cause that since it's just fatty acids. Are you taking anything else...
I used to work for a Vitamin Shoppe. We sold anything from Muscle Milk to Beverly. When it comes down to it, Protein is protein. The only difference are the sources and nutritional value.
Don't buy...
4 weeks is hardly enough time for a bulk. Just bulk until you get to a size you like. I was 145 when I started lifting and now I'm 215. I'm definitely going to cut now.