You should have done a little more research before purchasing my friend. The primary issue is that you are wanting to experience Dextromethorphan, but you've gotten a product with other unwanted substances in it. Guaifenesin has nothing to do with the dissociative anesthetic effects of Dextromethorphan and in fact, often contribute to what users might describe as a "difficult experience". This is because the above drug is known to cause side effects ranging from nausea, to vomiting, to general malaise, even in lower dosages. Now, if you're taking several times the recommended dosage, it can easily make you sick and uncomfortable.
If you're looking to just take a little DXM to help you sleep or something, I would say you're fine. However, if you're looking for a true dissociate trip, you need to go and acquire a product that contains only DXM. They have bottles of liquid capsules in the United States that contain only 15mg DXM and they are the choice for most people who know what they're doing with DXM. I would really recommend acquiring a sole DXM product and not a combination product like this or Nyquil, which contains a bunch of other nasty shit.
I apologize for the brief foray into mild sourcing, but I thought it was in context with helping the OP.