She shouldn't have them, as she's on Stronghold (flea, tick, etc stuff,
like Frontline), but Meep's got these little bumps inside her ears -
mostly toward the tips - and a couple more of them, with bloody middles,
 where her hair is thin between her eyes and her ears.  She doesn't
seem to be particularly itchy, or sore when I touch them.

What could be biting her, and if the Stronghold's not enough to keep
them at bay, what could I be using?

She's mostly indoor, but with the warm weather, she's spending a good
bit of time outside in our garden here in England, and was exploring in
Scotland with us last week as well (posted about it earlier) - it's
possible she picked them up there...