Back injury

Question
My chihuahua went out late night and was spooked by an animal and apparently ran into something in her retreat.  She developed a small lump on the lower RH side of her back, and she initially was walking around fairly hunched and contorted.  This AM the lump had not changed significantly, and she was rather lethargic and not interested in eating.  She has since begun moving more freely and is less contorted.  She also ate her breakfast, although she is not her normal frisky self.  Is there anything we can apply to the lump or other "therapy" for her back?

Answer
I am not a vet and have no medical training (as stated in my profile), but I would think that you could do the same as for humans, apply an ice pack to the injured area.  You should get her checked by a vet though, just to make sure it's not a puncture wound (either a bite, a sting or cactus, etc).  The lethargy and lack of interest in food could have been pain caused, but again, make sure it's a closed wound and there are no foreign bodies in the bump.