He may need a little more A time if he's doing 45min naps. At that age, its common for babies to do one short and one long nap. If he's waking at 5.30am and unable to get back to sleep, I would probably try for a morning nap around 9-9.30am and let him sleep up to 45mins and then offer the afternoon nap around 3-3.5hrs from when he wakes. So something like this:
5.30-6am - wake
9.15-10am - morning nap
1.30-3 - afternoon nap
6.30pm - bedtime
Could he be teething at all?