sleep regression or growth spurt?

Siobhan
So my LO is 13 weeks old. At 12 weeks he was super fussy, ate (I Bf) loads and often and didn't want to be put down or held. We made it through and he went back to being his happy little self. 
Well this week his sleep has been getting progressively worse. His normal (I say normal as in his routine that he responded best to. I know it's still a bit early to put on a schedule) schedule was 7pm-11pm, feed and back to sleep till 3, repeat and then he slept in between 7-8. Naps weren't as good- with maybe one solid 40 minute nap in either the crib or glider. The other two naps would be 20 minutes.
Now this past week his sleeping has been all over the place- yesterday he napped for three and a half hours (on me), and has been getting up between 5-6am all week. The past two nights he's been up at 9 and absolutely refusing sleep till around 11, and then he wakes up at 2,4, and 5.
Needless to say I am tired! And luckily I've been getting some sleep when he is napping, but I'm at a total loss of what to do or what this could be! 
Is anyone else going through this? Any insight or advice would be helpful. 
Thanks for reading this!