6 Month Old Male Cat Constantly Meowing

Question
(Apology in advance for the length of this question. I'm only trying to provide enough detail for a proper evaluation.)

My current situation is as such- I have a total of 3 cats which include 2 females @ aprx 1 year old and a male @ aprx 6 months old. The male is a rescue kitty that was separated from his mother at only a couple of weeks at most. His mother rejected him. The 2 females were adopted @ 10 weeks old from a shelter & were already fixed. The male was most recently fixed on Oct 18th. All 3 cats have been evaluated by a qualified vet. I keep all 3 cats inside my bedroom when I leave the house and when I'm sleeping because they always find something to get into when I'm not around or not looking. I have 2 behavioral questions.

1) Recently the male cat has started crying and yowling under my bedroom door whether I am inside the room or outside the room. Prior to him being fixed he only cried for a bit when I would leave the room, but never when I was inside the room with him. The other 2 older cats don't meow at all for the most part. I first assumed the crying was possibly separation anxiety since I have taken care of him from only a few weeks old. But now I don't know what to make of it since the yowling has progressed to being almost constant. He doesn't cry when he is hungry or when I am playing with him. I was thinking the recent fixing may have something to do with this change in behavior but of course, I'm no expert. Can you shed some light on this change in behavior for my young male?

2) The interaction between my young male and the 2 older cats is great. They play and nuzzle with each other, and for the most part they barely ever actually fight. The young male has taken a liking to one of the older cats in particular and shows his affection by sucking on the fur on the back of her right ear, which in turn makes her fur all yucky. He doesn't just do it for a few minutes, the sucking could go on for as long as she puts up with it, which has been almost all night sometimes. Watching him, it seems that the sucking calls him down (side note: he has an almost unlimited amount of energy and almost never stops moving.) When the older female wants the male to stop she has to escape to the top of my TV, which the young male can't reach because he is quite small compared to her and can't jump as high, yet. If I try to separate the male from the female while he is sucking he will do whatever he can to get back to her to continue sucking. Even distractions don't really work. I can only assume that this behavior has something to do with how young he was upon seperation from his mother. I'm just looking for some explanation to this behavior and if there could be any "consequences."

Thank you for whatever explanation you can provide for the 2 situations described above. For the record, the 2nd older cat that the young male doesnt suck on doesn't care too much for the young male, but also doesn't hate him. She seems to tolerate him, but for the most part likes to remain untouched, unless I'm petting her.

Thank you!

Answer
I have the feeling that you may be right about separation anxiety or anxiety in general being the cause of both behaviors. I would suggest that you not worry too much about the sucking behavior, it is certainly due to his early separation from mom and likely some insecurity as well, if the cat who was being sucked on was annoyed by it, she would let your little one know. The crying is likely due to anxiety. My youngest cat whom I rescued from the streets late one night does the same thing when shut in somewhere or left alone. If the meowing is causing problems with your neighbors or your sanity I would suggest asking your vet about a temporary course of anti anxiety drugs and a behavior modification program to help kitty with his persistant vocalization. To start you off until you get back to the vet I would suggest that you reward your little one with something important to him for periods of silence. For some cats this is play for others it is different types of food - beef or lamb baby food is fairly yummy to most cats and small amounts can be used as rewards for desirable behavior. You seem to be describing an incredibly insecure kitty, so I still say that anti anxiety medication prescribed by your vet will be useful in your behavior modification program. One thing that you need to remember during this process is to be patient, try keeping a journal so that you can see small improvements, the other is to be as consistant as you can or you will not be successful. Best of luck, keep me posted as I would like to know how things turn out for kitty and you. If you have any further questions, please do not hesitate to contact me, I will do the best I can to find the right answers for you and your furry friends. Thanks for providing as much detail as you did, I got a pretty clear snapshot into what it is that your issues are and hopefully with the help of your vet we can solve this problem as a team.