What Does It Indicate If A 6 Month Old Child Doesn't Reach Growth Milestones?

6 month old female, with decrease in her milestones equivalent to 1 month development presenting with epidodes of nistagmus , and what is believed seizures, on eeg there was evidence of all kind of brain activities increased reticular activities, sob, irtitability 2 or 3 of this episodes during the day , she will suck adecuate , when in resting mode she will be quite with normal tonicity but way of of what is believed for a 6 month baby , patient wouldt roll over and will not follow stare of faces around her. Kindly give opinion.