Does he wake up at the usual time? Does he sleep thru the night as well as he did before?
If the lack of a nap is the only change I'd guess that it has something to do with his cold. Dairy will thicken mucous. Gassy makes me stay awake at night. Does he eat any solid food for lunch? Has that recently changed?
My granddaughter was actually allergic to milk and not lactose intolerant. That's something to check. We gave her rice milk. Be careful about using soy. It's a common allergy. And the soy does have hormone like something in it. That's why using soy is helpful for menapausal women.
If he's getting more sleep at night he might "think" he doesn't need a nap. I'd guess he goes to sleep earlier because he is tired. I'd try keeping to the earlier schedule. He doesn't have to sleep during the pm nap time. Just put him in his crib. If he cries go in and check that he doesn't need anything and leave. You'll probably have to do this several times. I'm a bit of a maverick. If I were you, I'd put him in his crib and then stay in the room, reading a book or working on handwork.
If that doesn't work in a week or two, I'd keep him awake until his regular bedtime if doing so doesn't cause him difficulty sleeping at night.
I took care of my grandchildren during their baby years so that my daughter could work. It seemed like they changed their nap times from time to time. I was flexible and just went with the flow. You could try putting him down earlier in the morning and/or later in the afternoon.
Notice if anything in his surroundings have changed. Such as a neighbor has started making more noise or he's had different activities. Is his room the same temperature as before? Does he have the same things in his crib?
