My baby is 19 weeks old and he just won't nap for more than half an hour which is leading him to just be cranky ALL THE TIME. He sleeps through the night and has been doing for just over a month, however, the last 2 nights, he falls asleep between 7-8 and he's fine up until around midnight and at that time, he seems to partially wake up and cry. He keeps his eyes closed and when we put his pacifier back in, he dozes. But as soon as the dummy falls back out, I'm back to square one and he stays like this right up until 7am. He was never like this before, when his pacifier fell out it would stay out until 7am no problem. He wakes up at least 3/4 times an hour through the night now. I must mention that he is teething but absolutely nothing works to take his pain away. Does anyone know what could be the cause or have any advice please?