The symptoms your rattie has can be caused by several different things, which is why it is important to see a vet, as vets can listen to the lungs, the heart, etc and have a better idea of what is going on. Different underlying causes often require different medications.
If the medications he was on were helping, he was not on them long enough to get better, only long enough for the symptoms to disappear ….. which is why the symptoms returned.
Since it is a long term problem, I would suggest baytril + azithromycin (10 mg/Ib), orally, twice a day. If it helps, then he will need to be on it for approx. 6 weeks. Rats need to be on antibiotics for at least 4 weeks and I find that mine need to be on antibiotics for 6 weeks. Here in Canada, you can get azithromycin from a drug store with a prescription from your vet. ……………….. if you find it does not help enough then doxycycline can be added to the baytril + azithromycin.
There are other things your vet could prescribe to help his breathing …. if you post a video, lilspaz68 might have some suggestions of what you can ask for (post video to youtube and put the link on here)
If the above doesn't work he may have a heart problem, and your vet could test for this with Lasix or benazepril. There are meds that can be used to treat heart issues in pet rats.
The dose of the meds will depend on his weight and on the strength of the medication (mg/ml) ........... a digital scale with a tare function is an important tool for rat owners. If you give us that information, we can check the dose for you. You can also look up the meds on
www.ratguide.com This is a vet approved site for rat owners - the info might be useful to your vet as well.
You will likely need another vet visit to get meds for your boy. Try to find a good vet with the knowledge and experience to treat rats, or a vet that likes rats and is willing to learn. If we knew where you are (prov and possibly city), someone might be able to recommend a vet
Also make sure it is not environmental. Any scents, dusty bedding, ammonia from urine if cage gets dirty or there is not enough air flow, can cause illness in rats. (I deal with that problem because where I presently rent, my rats have to live in an enclosed room that does not have a lot of airflow - I use air purifiers with a permanent hepta filter and replaceable carbon filters and it helps a bit)
Hopefully lilspaz68 will respond as she is much more knowledgeable
Can you post a video of your boy on here so we can see his breathing? (post video to youtube and then put the link on here)
As for temperature, the temp best for rats is in the range of 65°-79°F / 18°-28°C (
http://ratguide.com/health/basics/v...14TaJTjPAuF9dueXAHkUzUDK0ioLm0jUTHpNmVoGfD__A)
You can cover the cage to try to keep it warmer (but they will likely chew holes in the material)
Only use the heating pad under one side of the cage so they can get closer or further away and do not over heat
Rats need to be kept a a fairly consistent temperature, changes in temperature more then 5 degree F in a 24 hr period will physically stress them and this can cause illness
I am not a vet etc, just an experienced pet owner
Can you add the prov you are in to your profile
If you post on the facebook grp Real Rat Lovers Want To Know, they may have some suggestions for you
For some info on what could be causing his breathing problems see
https://www.ratshackforum.com/threads/reference-thread-read-only.35894/
I understand your frustration and I hope this helps