Stressed

So stressed out. Got a puppy 4 months ago ever since my nearly 4 year old sons behaviour is shocking 😣 constantly naughty ignores everything you tell him not to do. Won't play with toys or watch TV or owt just runs rings round me. I'm due to have a elective section in 2 days and I'm so worried how I'm going to cope with new baby recovery and a naughty boy. I have 3 older boys so know they will help when theirs no school but I'm just at my witts end with my 4 year old. Don't understand why his gone from a good little boy to changing once got the pup.