Hi Staceyshoe,
I can't tell you what's going on with your son, since I'm not a clinician, but I can tell you some stuff about what is "normal" (I'm a professor of cognitive psychology). Neurotypical kids are language sponges. They often learn new words from a single exposure (a process called "fast mapping"). Their sentence structure is still relatively simple at age 4, but they generally get it right. Even in the two-word stage (usually age 2 or younger) they use appropriate word order, constructing two-word phrases such as subject-verb, verb-object, or adjective-noun.
So what you're describing -- great difficulty acquiring verbal information, incorrect word order -- I would say are signs that warrant seeking a professional opinion. You already know what your son's areas of strength and weakness are, and a professional can help you to get the resources you need to help him thrive and be successful with the type of brain he has.
