Ooh what to do ... what to do???

Lately my little Noah has been having a hard time at night sleeping. I know hes teething but its more then that. Usually if he is not feeling good or his teeth hurt hardly anything calms him down even me rocking him he will still cry. The past few days hes been fine all day long goes down for his naps just fine he plays fine but then when its bed time he will go down ok for about 15 20 min. The boys usually like to play around in there beds before falling asleep. Then he will all the sudden get really upset and start crying. I let him cry a min to see if he will just stop but he doesn't he is a little cryer he will keep going tell his voice is about to give out or he like almost passes out! I know its sad. I always go in there to comfort him because I don't want him to wake Elijah. I know it cant be his teething because he is fine if I hold him or stand by his bed. As soon as I walk away he will freak out and cry. I read about separation anxiety and I know he has it bad with me! He wont go to any one but me he will to James if its only us in the room but if were around any one he will start crying and he will only go with me. Its so bad that he was sitting on the floor and my mom came and sat next to us and he started crying! I was sitting right next to him and no one was holding him he was fine and he knows my mom very well and he cryed with her sitting there. I'm not sure how long this will last but he is going through it very bad! I have to literally stand next to his crib for about a half hr. until he falls asleep! Its terrible I want to just let him cry but I got Elijah to think about. Poor guy hes been so messed up with his sleep because of Noah he will be asleep then wake up because of Noah's crying then I will finally get Noah down and Elijah will be wide awake and he will start playing then he will wake Noah! By the time there done with switching its almost midnight! And then the next day they are falling asleep while playing Elijah mostly. He actually fell asleep while playing in his activity station lol. I'm sure its a faze but oh my is it a bad one! haha Noah is definitely my baby he is so sensitive and he is the one who always gets hurt and he is the one that takes everything worse then Elijah lol such different babys I have.