Kitten issues

Question
Hello there, I recently found 2 kittnes out side that some one dumped.  They are brother and sister or atleat appear to be.  I have been taking care of them now for about 3 months while trying to find them a good home but since they are not little babies no one seems to want them.  The male has gotten a lot larger then the female.  He appears to be strong healthy and bad.  Typical male cat.  The female on the other hand seems to be sickly.  She is very skinny, has oh my HORRIBLE breath, doesn't seem to groom her self enough (looks kind of oily and some times has litter to maybe poop some times stuck to her for a day or so until I get her cleaned back up).  She has these small lumps on her, one under her front leg, and one under the right side of her jaw.  Right after I brought them into the house she got into a tube of equine ivremectin that was put in the trash, it was empty but she licked off what ever was around the edges and she over dosed on that.  So I took her to the vet and she said just take her home try to get her to eat and drink as much as possible and hope she makes it... The kitten acted like she was drunk, unable to walk streight, meow, or even eat right!  But she recovered and I thought we would be ok.  Then the breath got worse and she didn't gain weight.  The weight made me think worms so back to the vet we went to get wormed but the vet said the equine wormer she got into was enough to kill everything and she didn't want to worm her again.  But she did find a sore on the inside of her mouth where it seemed as though her baby teeth were comming out and her adult teeth were comming in so said the vet.  It was bleeding on both sides very red and swollen.  So we put her on soft food only and the vet said it should go away in a few weeks.  It has now been about 2 months and the gums have healed but she has a sore on the edge of her tounge close to the place the gums were effected... I have been watching it and I think its getting better but its been a long time... She will eat atleast 2 cans of wet food a day, wont touch dry food even if I put water in it to make it mushy.  Isn't gaining a pound, and the breath oh my!  The lumps bother me the vet said not to worry about them unless they get big or start to bother her but shes still a baby why are they there?  Any help would be greatly appreaciated since the vet doesn't seem to know anything else to do but let her go and see what happens!  She is active runs around and plays and stuff but her bother is litteraly twice the size she is and shes so skinny!  Thanks in advance!!

Answer
I would take her back to the vet's and have her tested for leukemia, FIV and FIP if she hasn't been already. It sounds like she has lymphoma, which is a lumpy form of leukemia.

If you have refused to have her tested in the past (on cost) then now is the time to get it done. She has some of the symptoms of it or FIV, which is like AIDS.

Sore mouths that don't heal, unthrifty, no weight gain, sickly, etc. One of the tell-tale signs of these diseases is the mouth issues and the lumps sound like glands that are swollen, a hallmark of lymphoma.

Is she has it, then the male might have it also. He may have thrown it off or maybe he is a carrier but isn't ill from it.

Either way get them both tested and soon. This is not from the ivermectin.
Please let me know what you find out.