Sleep problems with infants are not uncommon. Two factors that often impact on sleep are routines and eating. More often than not when an infant is struggling to sleep it can be because they are not eating enough when being fed... so you may wish to try to get your child to eat more. If this is problematic they may be experiencing some problems with eating which may mean a trip to the pediatrician. Another contributing factor can be inconsistency in routine... this might mean keeping your child up a bit later to establish a night time pattern followed with a daytime nap... putting a routine in place might take some time to achieve but it is worth it over the long term. One final thought, it is important to ensure a child is not over-stimulated via too many activities, people or access (purposeful or accidental) to screen devices.. .try to ensure that when time for sleep is approaching things are calm and devoid of distractions. If none of these things help it may be time to see a professional for there might be something else going on that an infant is not able to tell you about.