Is it possible I accidentally ingested a little bit of bleach?

I was cleaning my kitchen sink a few days ago with warm water and bleach when my coffee thermos accidentally fell in. I immediately rinsed it and washed it with a sponge and dish soap and tried to get the bleach residue to come off as best as I could, but the last two days after I've had coffee from this thermos I've had the most painful stomachaches. Is it possible this is from the tiniest ingestion of bleach (because it seems unlikely, the only place bleach could still be is inside the special part of the cap) or am I suffering from stomachaches for some other reason besides this? Just curious. Thanks!