Do you have a schedule/routine in place? How many naps is he getting? If you're interested, there's a FB group I highly recommend that helped my family greatly when it came to sleep. I can send you the link . They run a free sleep seminar every month and give lots of tips and tricks as to what to do at different stages.
Sleep consultant here 👋🏼 I would assume your baby is on 2 naps, but def move to 2 if they’re still on 3. If 2 isn’t working (sounds like it isn’t), then you can try 1 nap even at 10 MO. Every baby’s development and sleep is different and I had to move my daughter to 1 nap at 10 months and it worked great. If you’re doing 2 naps, wake windows should be about 3.5 hour and if you’re doing 1, a 4.5 hour morning wake window, a 3 hour nap, and 5 hour afternoon wake window works well. You should also try pick up/put down to get him to I totally fall asleep. It’s just what it sounds like, pick him up when he cries, put him back down when he’s calm and keep repeating until you put him down and he goes to sleep (they eventually will even if it takes an hour the first time). Good luck and you can always check out my website for more hhsleep.com