Got to love in-laws. I know I already love my boyfriend's parents and can't wait until we get married so we spend even more time together!
I would recommend taking your bird to a vet. If it swells further it could restrict breathing, and if it gets infected that could really be a problem also. Since they are so small and have such fast metabolisms, an infection can do a lot of harm in a hurry. To find an avian vet in your area, go to http://aav.org/vet-lookup/
I recommend searching by state, as searching by city somehow eliminates even results that are close by in the same city. Call around to a few vets, as some charge a whole lot of money, just because avian vets are a little harder to find. A decent vet will charge between $30-45. Best of luck, and sorry that your in-laws are no good.