Firstly, I would beg to differ about the pain; there is a limp because there is a pain. Now, a limp in a front leg can be for a long list of reasons, sting could be one of them. Foreign body in the foot, infection in the foot … is there any swelling? But there could be an injury anywhere else on the leg and there even could be a neck issue resulting in a front leg limp (Jasmine had that).
If you’re comfortable doing that I’d start with a thorough inspection of the foot, toes, nails, looking for any swellings, lesions, nail injuries, foreign bodies … If you don’t find anything on the foot, it could still be the foot (Cookie had a piece of a purcipine quill embedded between the toes which was totally invisible until finally it got pushed out with pus. But it also could be something else all together.
My recommendation is if you don’t find anything obvious, see a vet. If you do find something obvious, you still may need to see a vet.
I would call my vet right away, or if they aren’t available I would at least call a 24 hour vet to get some sort of professional opinion if you don’t get a response from a medical professional on this website. I hope everything is ok!
Sounds like she had an injury that wasn’t seen and it abscessed. Get her to the vet in the morning.