When DS was a toddler I was constantly googling "apraxia of speech"...I even joined an apraxia forum. I was more worried about his speech than his motor skills at that point. He was ultimately diagnosed with DCD. He is now 8 and still has difficulties with certain sounds and his prosody is a bit odd. Problems with motor skills are common with kids with apraxia of speech. If your DD was an early talker, though, that doesn't seem to fit very well.
DS has a subtle genetic abnormality and all the medical professionals like to pin his issues on that (a balanced translocation). I have the exact same abnormality, as well as other members of my family, but no one else has issues like DS. It is not an obvious abnormality, we had him tested at birth because I knew I was a carrier and it affects later fertility. The geneticist says that it can affect him differently than the rest of us carriers--there may be a microdeletion there that the rest of us don't have, etc. On the apraxia formum a lot of the kids seemed to have some sort of subtle genetic disorder. It may be worth a visit to a geneticist to see if anything stands out.
DS also has a borderline chiari malformation but I don't really think that ties in in any way. Interestingly, his first MRI was interpreted as normal, but then when he fractured his skull and the neurosurgeon went back through old records and looked at that old MRI from 1-2 years earlier, he said it should have been reported as an abnormality.
