3 is a horrible age YG - ds is just coming out of the really horrible bit, and I can pretty well reason with him now. Could this be a reaction to your dd2 having been ill last week?
With ds, I just try and have activities stacked up, so as soon as he's tired of one thing, it's on to the next. Knackering for you, but he definitely sleeps better when he's had lots of stimulation. Can you do lots of Easter craft things? We spent the morning today buying a few bits and pieces to make cards etc, so he could choose the bits, then spent the afternoon making cards (we did chicks, with potato printing for body and head, then ELC eyes stuck on and beaks), and have also made an 'Easter Egg Box' - painted an egg box yellow, then stuck ELC pom poms on top for Easter eggs, shredded some tissue paper, put in box, made yellow pom pom for chick (that was great - took ds AGES!), stuck on ELC eyes, made beak and voila!
Hth - it is a really trying age, especially with a little one! Hope tomorrow is better.