It sounds like he may just be going through a phase of separation anxiety. Kids go through a few of these phases as they develop. Or, he could be teething. Babies get their first set of molars around their first birthday and some get them earlier than others. Either way, it sounds like he just needs more attention and comfort from you. It may be irritating, but you have to give your baby what he needs. If your son is teething you should try giving him homeopathic teething tablets, they're amazing!My son is 18 months old and he's suddenly requiring more attention, most likely because he knows we'll be having another baby in less than two months. He's started hating naptime and bedtime, to the point that he'll throw tantrums and will make me tuck him in (complete with hugs and kisses) multiple times. He's even started waking up in the middle of the night and half the time won't sleep until I bring him to bed with me. It's frustrating, he had been very good about sleeping. But I know he just needs more right now so I'm happy to give him what he needs.