We've always gotten nighttime fevers with teething...up to around 103...but usually in the low 99/101 range.
Of course, sometimes colds/flus/poxes come with fevers at night, but not the day...but if there are no other sypmtoms it's *probably* teeth
You can put the liquid medicine in a cup of hot chocolate just before bed, or mix it up with juice, or you can do it preemptively with the syrup or a chewable with dinner. We always had our best luck with hot chocolate...but then that's because it's OUR son's favorite! :) Find something yours likes and mix it up.
For the record :) BOTH tylenol (acetaminophen) and motrin (ibuprofen) are fever reducers. Sometimes one will work better then the other for some people. You can actually take a full dose of each, at the same time, if you're desperate, or if one isn't having much effect. The "not having much effect" on the fever is *Usually* do to the strength of the fever...and not the efficacy of the med.