J.R.
I understand your frustration. My daughther is a terrible sleeper- she has been from day one and still is at 2 years old. It is so stressful, but know you are not alone.
First of all, he's definitely not getting enough sleep. My 2 year old still naps every day and gets more than a total of 8-10 hours of sleep- a 10 month old requires much more sleep than that. He is probably so overtired that he simply can't settle down. It sounds totally counter-intuitive, but sleep begets sleep. When my daughter has a great night's sleep (like 12-13 hours), she will turn around and have a fantastic nap the next day (2-3 hours); when she gets a bad night's sleep (like 8 or 9 hours), she is miserable the entire next day and takes a short nap if she even naps at all. Now, the trick is to get him on a routine so that he's gets to that point.
I would absolutely re-introduce the naps. Most 10 month olds still take 2 naps every day. When my daughter was 10 months old she was taking a morning and afternoon nap every day. She would go down for a nap about 2 1/2 - 3 hours after waking up. I would also give him an earlier bedtime. You don't want to just suddenly start putting him to bed at like 7, but every day push his bedtime back about 15 minutes. At 10 months my daughter went to bed really early (like 6-7 PM). She did better going to bed early because she would get a good night's sleep- if I kept her up later, she would wake up even earlier in the morning and be miserable and it just starts the vicious cycle over again.
My daughter has always taken forever to fall asleep (it is completely usual for her to take 2 + hours to fall asleep!!) This does not mean she's not tired- it just means she takes a long time to settle down. Your son might be the same way. For almost the first year of her life I rocked her to sleep. Around a year I had to resort to CIO because I couldn't sit and rock her for hours and hours every time she needed to sleep. She still takes an extremely long time to fall asleep, but now she usually plays quietly and happily in her crib to settle herself down. I leave board books and stuffed animals in her crib so she play while she's settling down. And if she's in her crib, even if she's not asleep, I will go to bed myself with the monitor so I can hear her if she really starts crying.
Hang in there! Sleep difficulties are truly some of the most frustrating and stressful parts of parenting. I can't tell you how much sleep I've lost over my daughter's lack of sleep! Good luck!!