Ds is 3.5 months old. He was gradually improving with his sleeping until 2 weeks ago. Back then he was consistently sleeping 6/7h without a feed (then waking 2 hourly). For the past 2 weeks his longest stretch has been 3/4h and then waking every 1/1.5h. I'm breastfeeding on demand and don't like the idea of leaving him to cry. Any advice?? I'm beginning to feel pretty shattered!