Could he be teething?

For the past few days Eric has not been himself.
He's been drooling, sucking on things, losing interest in eating (now that is not like Eric. Normally he has a big appetite) and unusually fussy. Also the other day, I noticed his cheeks were red. I thought he had a fever but when I checked it, it was normal.
Today was even more bizarre. He woke up around 8am crying. He tried to soothe himself by sucking on his thumb but that didn't work. Something was obviously upsetting him. Since David and I have been putting him to bed at 8pm, we have both noticed that he has been waking up in morning with a smile on his face. He seems to be well rested and cheerful. But not today. I think he woke up on the wrong side of the crib today.
So as I was about ready to cry myself, I took a deep breath and changed his diaper and fed him. That seemed to work. One other thing I've been noticing recently is that he doesn't seem to want to nurse first thing in the morning. When he's too hungry, he can't get enough from me to be satisfied so that he stops crying. It could be a growth spurt or maybe my supply is decreasing even more? I don't know right now.
What I used to be able to do is to nurse him first thing in the morning for about 30 minutes. Then I would sit him up in his infant rocker chair and let him play with his toys. He would be fine for a while, or at least long enough for me to take a shower or have some breakfast. Then I would feed him a bottle of formula.
For the past 3 weeks, it has been different. He doesn't want to nurse as long.

After I fed him this morning, I burped him and put him in his chair. I ate some breakfast and I had some bottles to wash so I started doing that. After about 20 minutes later, I looked over at him and he was asleep. He fell asleep in his chair again. (This is something that this one strict book that I've been struggling to get through, frowns upon). So I put him in his crib. That was about 10:30am. And he's still asleep. This is the longest nap he has ever taken during the day (except for when he was a newborn). Maybe he's putting himself on his own napping schedule.

I guess now is the time for me to fold the laundry and finish washing the dishes? Ha!