I just experienced the same exact thing two days back. However mine was because someone gave her chocolate hence it caused her colic. And because of this, she can’t sleep so she’s overtired. We applied ruyee oil on her tummy and soles of both feet and let her nap as much in the day then forced an early bedtime to turn back the sleeping time.
Since your LO is 8mos, although the symptoms are the same, you might wanna check for teething.