At a year and a half old - kids wake up for all sorts of reasons.
Right around 2 years old they can start having nightmares, fears of monster under the bed, etc.
Their imaginations go at full tilt during the day and it doesn't stop at night.
Some kids really change up their napping/sleeping habits around this age.
Our son had his tonsils/adenoids out at 4 yrs old and he slept better afterward than before surgery because he wasn't snoring anymore.
It can take a few weeks for the sore areas from surgery to heal up.
Talk to your doctor about pain management and recovery time.
Some kids need pain meds (liquid Tylenol, etc) longer than others.
It's important to keep him well hydrated and feed him soft foods - nothing hard or crunchy.
He can have all the jello he wants.