I'm sorry. I have to wholeheartedly disagree that you should just let him cry and go back in and check on him periodically. Put in earplugs and just let them wail? Are you kidding me? That DOES NOT teach your baby to sleep. It teaches him that he has been left alone and for some reason you won't come to his rescue like you always do. And it floods his little system with stress hormones. Even Dr. Ferber (who's method is commonly called the Cry It Out method) says you do not start that kind of sleep training until at least age 6 months. In my book you never start that kind of sleep training.
Babies, all babies, have to be taught how to sleep. You taught your son how to sleep propping a bottle in his mouth and turning on the tv. I can't even begin to imagine how that came to be. I'm not trying to be hyper critical. I understand tough times with baby. My first was 8 weeks premature, came home on a monitor, meds 4 times per day, didn't know how to breastfeed so I pumped round the clock while teaching him to breastfeed, etc. But you have to teach your son how to sleep. Please stop propping a bottle up in his mouth. That is the quickest way to rot his teeth when they come in and it a chocking hazard. Please turn off the tv. His little brain isn't ready for all those light and sound images. Get to some old fashioned parenting with your little one. Teach him how to sleep.
You need to establish a solid routine at night. Bottle, bath, jammies, rocking/soothing him till he is asleep, then while staying close to him-as close as you possibly can, lay him down in his bed. If he wakes up soothe him again back to sleep and lay him down again. It will take several weeks of literally doing and saying the same things every night before he learns what to expect and what is expected of him. Please read Dr. Sears Baby Sleep Book. It's a kinder gentler way to teach baby to sleep. I held both my kids till they were asleep and they learned to sleep thru the night just fine.
Also, baby needs to be napping at least twice during the day. Sleep gets you sleep. A well rested baby will sleep better at night.