Thanks guys for your answers.

I saw two vets , the first was bad (no knowledge) , the second is a specialit reptile , a clinic vetenary specialized in reptiles ( well known in my country). He's for me very competent.
I don't know all the drugs He used but the more used (baytril,..). The snakes are stayed two months at the vet so I didn't cure them by myself. It was to avoid contamination at my home.
The snakes was sick before to come at my home, i made the mistake to don't check well the mouth before to buy.
At my home , i have professionnal alu rack with hot spot 33°c , all my snakes are perfectly healthy and i don't think the problem is coming from me.
I rather think , it's a problem at the ex owner home, he didn't respect temp,.., maybe he fed the snakes during low temperature...

For the moment , they continue to feed , medium rats , one time a week. Sometimes they seems to be better and sometimes they have a bit deformed mouth with saliva.
I don't know...what to do . I can try an other vet but it begin to cost expensive (already 400euro!) and who choose.. i already saw the best in my country..

(sorry for my english, i wish you will understand all)