There is little worse than realizing that another company has been using your trademark to promote its copycat products. Your customers have been leaving negative feedback stating that you sold them cheap, dangerous items. The trouble is that those aren't your items and they're not your customers. It's driving your business into the ground.
Trademark law is an important kind of law in America because of situations like yours. It protects those who own marks that distinguish their goods from others' goods from other businesses stealing those marks or using similar marks that could cause confusion. A trademark's purpose is to make sure that consumers can accurately know the source of services and goods when they see a mark instead of having to question if the mark is just similar to the service or goods they want.
Trademark rights are only protective within a specific geographic area. For instance, if it's used across the United States, it isn't necessarily protected outside the country. Keep this in mind if you intend to sell your products internationally.
Registering your trademark is a necessity. It gives you grounds to sue in federal court if someone infringes on your trademark. Registration also provides national notice that you have made a claim of ownership for a particular mark. Additionally, you may have your registration recorded with the U.S. Customs Service to prevent goods from other countries using a similar or copied mark from entering the United States. If you find that some did get into the country or that others are using your trademark, you can pursue legal action.
Source: FindLaw, "Intellectual Property Protection," accessed May 01, 2018