Let me start by saying, I'm not a vet and you should always check with your own vet first.
If your snake started blowing bubble immediatelty after you gave him oral medicine there's a good chance you're injecting it into his lungs. That's one of the problems with abministering oral medication but I'm assuming your vet explained all of that to you already.
I agree with Bogertophis you should be consulting with a vet, I've seen a lot of misinformation provided online.
I learned the hard way that doing things on the cheap can end up costing three times as much in the end. I now have a $700 piebald ball python that i rescued with a RI and because i was to cheap to pay $150 for a culture I ended up giving him two antibotics that were not affective because the infection was resistant.
It cost me $180 for two additional vet office visits and another $140 for the two antibotics that didn't work on top of the $180 for the next office visits and the followup, $80 for the correct antibiotics, and $150 for the culture. It took three months with the correct antibiotic to get him healthy.
It could have also been another $200 for an X-ray but I told the vet, I'm going to assume it has developed into pneumonia and should be treated accordingly.
That was two years ago when he was 600g he's now over 1500g and I'm breeding him this year to try and get some of my money back.