In order to become fluent in two languages, it is important to have exposure to those languages during the very early years of life. Unless your child develops some speech problem (like stuttering or fear of talking), I would continue to talk to him in both English and Spanish. However, choose one as the main language of the household and talk to him mainly in that language, but help him to understand the secondary language.
With the names of objects, it is easy: “We call this leche, Anglos call it milk.” Verbs (action words) are a little harder, but it can be done: “Yo tengo un lapiz; I have a pencil.” And be patient: with two languages to be mastered, both take a little longer. In the long run, though, your child will benefit from early exposure to both Spanish and English.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.