Is my baby lactose intolerant?

We go to see his doctor on Tuesday this week so definitely will discuss this with him, but I would like yalls opinion if this ever happened to your baby. We was feeding him Gerber Goodstart but he would spit up about a ounce of it after every feeding, so I got it switch to Gerber Gentle (his wic nurse recommended it) but he is still spitting up a ounce of it after most feeding and he acts like he still hungry, and like it's hurting his tummy. I don't think he's getting the nutrition he needs and he's not getting full from it. He is a month old today so I try to only feed him 2 ounces but sometimes he eats 3. When he eats 2 ounces he is hungry the next 30 minutes. Has this happened to anyone? Opinions please! Oh and he is constpatited most the time, usually when he poops its like solid clay!