Just some ideas to think about...when we went away for the holidays, our kids were WAY more stimulated than they are at home, where things are familiar, more mellow, etc. We had relatives in their faces all the time, lots of activities, new things to explore, so it tired them out faster. (we have a 2 yr. old and 5 month old). Both kids needed less A time for naps due to this overstimulation, and we had to adapt to keep them rested. Perhaps your baby had a similar experience of getting tired out more quickly, and led to an accumulation of OT-ness which started to affect night sleep? How are naps right now?
I have no idea if this is at all relevant in your case, but you might try reducing A time just a bit for a while, and see if that improves things at all?
I hope you get some other ideas too...
katemom