So during the day Lucas gets powdered formula, and the ready made liquid at night if he wakes up. Ever since i switched to the step two powdered formula he has been having constipation problems. he has never had any problems until now. They are not really hard poops, and he doesn't seem to have problems but they kind of stick to him and are more solid and today i noticed that he had some blood in his..crack? i have been giving him prunes since he loves them so much and they work well but then he is back to these types of poops again. should i just change the formula? what types have you had success with? i noticed there are two different kinds of the step two so maybe i could try the other one? He is getting Similac and that is the kind he has always had.