My rat, Jericho.

Question
I have a gorgeous boy rat, Jericho, who would be about 2 years one month old.. needless to say he is my whole world, and I would do anything for him..
Last year, he developed breathing problems, very loud "blocked" sounding breathing, and he began to do a clicking sounding, gasping breathing. I knew he wouldnt be able to hold out for his vets appointment, so we found an emergency vet clinic to take him to then and there. He had to stay there for a week in an oxygen box and was on two different anti-biotics. After the week, he was able to come home and was fine(they diagnosed him as having pneumonia).. once his anti-biotics ran out, he started to get his breathing problems again, but they werent as bad- so the vets said to keep him on his anti-biotics (which are baytril and clauverix(?)).. lately, once more, his breathing has taken on the loud, blocked sounding breathing.. and the vet said that he probably has the "rat version" of tuberculosis.. and increased his meds.. but in increasing them, he's been put off his food.. I dont know what to.
We cut down his meds to their original dose, and he is eating again, but his breathing is still loud..
I was wondering what your thoughts were..
I know his age is considered old.. but I dont want to consider him taking the "forever sleep"... I'd do anything to make him better, so cost is no issue.
Also, this morning, my husband found a lump about the size of a pea on the side of his mouth (near his whiskers on that side)- kind of has the "hound dog" droop? There isnt any "head" where puss could escape, and it isnt weepy.. husband was able to feel it and said it felt a little squishy, but couldnt be sure because Jericho is such a squirmer. He doesnt appear to be in any pain with it.
I've been calling the vets all day leaving messages, they still havent gotten back to me...

Answer
Your vet is describing mycoplasmosis, and although its not directly related to TB like humans get, myco in a different strain causes TB in humans.   What happens is, the rats lungs become scarred and sometimes blistered.  Your vet should also try steroids for inflammation.  Is this in his nasal passages?  Sometimes myco can even destroy tissue in the nasal passages.   Your rat is not old, btw.  Old is 2.5 years and 3 years old and up.   I just lost my old boy who was 3 weeks past his 4th birthday and also lost another rat last week, my last remaining rat, who was 33 months old.   I did not really consider Santana old, just getting up there in age.

I think the lump you found on his face may yet be an abscess.  It takes a bit of time for a head to form, sometimes a scab forms first, but you can help encourage it along by holding a warm compress on it and trying to get it to pop.  

As for him not eating due to the meds, you can try baby foods. I bet he loves them.  I would try most anything at this point, even scrambled eggs.  Most rats that have respiratory issues prefer to lick rather than chew since it is easier to lick rather than exert himself by chewing.  It takes less air to lick.