Should we go back to sleep training?

As I've posted over the past several days, I believe DS is teething because of some cranky periods, but mostly because of the whole hand he has stuffed in his mouth all day long. If we give him Motrin (generic) before bed, he's been going right down without a peep and STTN. I was going to try Hylands Teething Tablets tonight because I don't like giving him Tylenol or Motrin every night for an extended period of time. The past several days, without Motrin before bed, he screams and cries. Thinking its teething, we'd go get him right away and hold him/rock him until he fell asleep and put him back in his crib. Some days he's been waking up again, others not. We did take him to the pedi. on Tuesday to get him checked for an ear infection, his ears are completely clear. He doesn't have any other symptoms of being sick - no fever, no cough, no runny nose, etc.

Last night we gave him Motrin before bed and he went to sleep no problems, but woke up at 1 AM. He was screaming and crying. Not wanting to CIO if he's teething, I went and got him right away and tried to get him to go back to sleep, as did DH. He sat in our bed and grinned at us until 4:30 AM, at which point he fell asleep on me. DH said to me, "Is he playing us, do we need to CIO?"

We had horrible sleep issues until 16.5 months. DS then learned to put himself to sleep and STTN. I don't know whether to say we did CIO or Ferber because it only took one night. We were undecided if we'd go in after five minutes or not and do the checks, when DS fell asleep within those five minutes, and after that one night, no crying at bedtime.

I hate to CIO if he's teething, but I think this also may be a sleep regression. WWYD?