You could be me a few years ago!!
In fact his first patents eve when he was in reception was so bad I went home and cried 
DS is 31 st Aug and I wanted to do the same thing ( shout he is a baby)...
Nothing clicked with him and he struggled with everything, scissors, writing, reading ( when he started reception he could not even read his name despite being in the nursery attached to the school for the year before) and I remember his reception teacher going on and on about him not being able to draw a perfect circle!!!
All the other kids in his class were getting reading books ( and bragging about it!!) and he finally got his first school reading book in feb of reception and did not have a clue 
But we kept practising at home and doing lots of colouring in etc to help him with his pencil grip and at Easter time he "finally got it" (I could have had a party!!) and he raced through the reading scheme and overtook kids who had had books from sept...
Fast forward to yr3 (where he is now) and he is doing great, so basically it does not always mean they will struggle because they do this early on in reception.
Fine motor skills can be helped by threading pegs, playing with clothes pegs (pegging them onto card) maybe try and find him some basic books about cars that he might want to try and read and most importantly keep reading to him...
On the concentrating thing maybe play a few games with him like snap and putting a variety of every day things on a tray, letting him look at them and then cover it up and see how many he can remember , but at his age keep it fun!!!