Sounds like you're doing the right things at night- probably just extended teething... we had rough teething, then SA, then more teething, etc etc...seems unending, but it does get better.
I am wondering if maybe he's getting ready to switch from 2-1 naps- sometimes that can disturb night sleep, and definitely will mess with bedtime as that last nap is getting to be late.
Hugs, hope that there are no NWs tonight, and definitely come for support when you drop to one nap.
FWIW- here is typical sleep for 18 mos:
18 months old 1 nap - 2 hrs
11.5hrs at night
So a 7:30 bedtime, and 6:30AM wakeup is 11 hours- not too bad. Day sleep could be cutting into night sleep some.