Sounds like it might be a combination of teething, separation anxiety & possibly getting ready to move to 2 day sleeps... just from moderating this forum, I have observed that the most common reason for a wake up in the first couple of hours after bedtime is overtiredness... the next is not tired enough. So you might like to try to work towards going to 2 day time naps... delay the first a little & then the second a bit too & you will probably have to have an earlier bedtime some days & some will be 3 naps & some 2 a day for a few weeks.
HTH