Parenting Advice Desperately Needed!!!

So I am truly at a loss of what to do with my son Ridge. I always swore I would never have a momma's boy or a whiner and I have both in one little boy. He's mute when it comes to words, but he fails to mute the sounds he puts out constantly. He is CONSTANTLY crying, whining, wanting to be held, wanting something I can't figure out because he won't talk. I truly cannot take it anymore. He was a great baby but as he's gotten older and he is now 18 months old, he's getting worse and worse. I know a lot of the patience issues has to do with me being pregnant but even Curtis is done with the whole deal. The thing that baffles me is that I will get more upset with him than Curtis and yet he still chooses to come to me or want me over Curtis which I don't understand or even enjoy which I am sorry to say. We've tried putting him in his bed every time he starts to cry for absolutely no reason, but it doesn't seem to do anything. He comes out and within a few SECONDS, he's back to whining and crying again. It is the most draining and frustrating thing. I feel so bad for Cambree who is such a great girl who seems to be getting the short end of the stick. Mom and dad are sick of dealing with Ridge that she gets bothered parents and lack of attention. I just don't know what else to do. I have another baby coming in a couple months and it truly scares me to think I will have Ridge still acting like he does with a brand new baby that will truly need my full attention. I watch him at times and want to believe he's in pain or something is bothering him (he still only has 7 teeth so he could be teething), or he always wants to be held so I link that to being in pain but I can't figure it to be the cause for everything. I am hoping there is someone out there who reads this that can shed some light on what I can do to curb this attitude. So anyone with ANY advice even simple as it may seem, please let me know because I truly don't know if I can handle too much more of things the way they are. Thanks for any help.