It may be because of his teething or it may be that he's going through a normal phase of separation anxiety. Help ease his teething discomfort by giving him some homeopathic teething tablets. They are amazing! Most brands treat four symptoms (pain, sleeplessness, inflamation, and irritability) and they work very quickly. Try to find the tablet kind, not the pellet kind. They dissolve faster and are easier for little ones to eat. They are completely safe and don't have any drug interactions. They work better and faster than Advil or Tylenol. I used to give them to my daughter any time she was fussy, whether she was teething or not and they calmed her down immediately.It's normal for kids to go through separation anxiety a few different times between infancy and toddlerhood. There isn't a whole lot you can do about it, especially as they get older. But for now, try talking to him a lot. Tell him everything you're doing as you're doing it and explain why you have to get up, why you can't hold him at that particiular moment, etc. Also try to bring him with you when you are going to be spending time in a different room. If you're going to be cleaning the kitchen or cooking sit him in his high chair so that he can see you and again, make sure to talk to him.