Agree with all of the above.
My boy had a nail (dewclaw) that was swollen aand ore, and it was at the nailbed. Eventually we had to amputate the toe - biopsy showed a weird reactive bone and some immune system cells that I can't remember. For the rest of his life he had weird swelling isues in that paw.
Not sure I would see an ER vet, but I would eek aa second opinion, or get a referral to maybe a specialist.
Tick disease could do this, and as mentioned, so can weird infections (staph, e.coli, etc), o I would try a trial of abx if one has already been tried.