Frustrated...

So I'm getting a little frustrated with Nathan's new sleeping pattern... for the past couple of weeks he's been very inconsistent! He was waking up once a night or every now and then sleeping through the night until a couple of weeks ago... then he was getting up twice a night... then the last two nights it's been THREE times! So the question is, what's the cause of this?!? Here are the possibilities that I've come up with...

~We phased him out of the swaddle over the past 3 weeks or so... starting with just one arm out, then both, and now we have him in a sleep sack. I think I may try swaddling him again tonight and see if he sleeps better because that would answer the question fairly easily.
~Is he getting a tooth? I think he may be getting a top tooth... he's been very drooly and has been sucking his fingers A LOT. I also thought I felt one possibly, but you can't really see it yet. Also, he bit me a few times yesterday... ouch! Alex didn't start that till much later... but at least it's not a full out tooth yet, so hopefully I can stop that quickly!
~Growth spurt?
~Ready for solids? The doctor gave us the go-ahead to start them if we want, but we waited till 6 months with Alex and I don't really see any NEED to start yet... unless it'd help him sleep better??
~Or... is it just becoming habit? This happened eventually with Alex and we had to let him cry it out, but he was quite a bit older, I'm thinking 6 or 7 months??? But I really can't remember. He does take a passy to sleep pretty often, so maybe we need to work on sleeping without it? Although we've mostly used it for naps, he doesn't usually need it to go to sleep at night and he has no problem GETTING to sleep or going back to sleep after being fed at night. (both of which were harder with Alex)

Then the next issue...
I haven't been letting him fuss at night for more than a few minutes... if he starts crying I have been pretty much going right in to get him (as soon as I can get myself out of bed that is ;) ). My main reason for this is that he shares a room with Alex and I don't want Alex to not be able to sleep. However, I think they've gotten used to each other at this point because Alex doesn't wake up through the night or in the morning when Nathan does any more, and Nathan doesn't wake up when we put Alex to bed either at this point. I'm thinking if we do let him cry for a while though, Alex would probably wake up. AND we're in an apartment, which is a whole new feeling too... I don't want to bother other people. Their room doesn't have any walls that connect with anyone else though (which is great), so it would just be if the people upstairs could hear him. My thinking is that maybe when we do decide to let him cry it out I'll put him in the laundry/bathroom again for a week or so to minimize bothering Alex.

Well... if you have any advice, I'd love to hear it!

On another note... a couple of cute Alex moments:
~We went to an apartment chips/margarita social the other night and told Alex we were going to the "clubhouse" for a party... his eyes got SO big and he was like "THE CLUBHOUSE??!!" then we realized he thought we meant Mickey Mouse's Clubhouse LOL... it's been his favorite show lately and Gary asked him the other day if he'd want to go there someday (referring to Disneyworld - we MIGHT be going later this year since Gary may be traveling to Orlando for work). Ever since, Alex has been asking to go there. Too funny.
~Looking at a picture of Nathan, "awww.... Nay Nay! He's so cute mommy!"
~Out of NOWHERE while we're running errands Alex says, "I wanna go to one more place" "You do? Where do you want to go?" "BEST BUY!" hmmm... wonder who taught him that? ;)
~"Guess what! It's the weekend!" "IT IS??? pamaw and pampaws house???" - (grandma and grandpa's) guess he thinks that's what weekends are for now haha.