Very likely could be teething, or a growth spurt. Or even a mixture of both.
My son started sleeping thru the night at about 5 months. Then at about 8 months he started waking every 1-2 hrs. That lasted for almost a week, then 3 teeth popped thru. Almost all on the same day. A few weeks later, he did it again, but it only lasted a couple days. That time he put on almost a pound the next week. We just went thru one more bout around a week ago, and another tooth cut thru with 2 more 'right there'.
What I have been told is, 'When it comes to babies, forget you have any other kids. You can draw patience from the others, but expect every kid to be completely different from any you had before.'