Contracting severe laryngitis overnight and acute bronchitis on second day?

When my doctor diagnosed me with laryngitis, he gave me antibiotics and said that I'll heal in about three days. I felt awfully crap.

The next day after the diagnosis (3:00 am) I started getting severe asthma. In the morning I was taken to the doctor, was diagnosed with acute bronchitis, and ended up in hospital.

My doctor was so surprised that the infection spread so quickly - in just 2 days.

How is it that something so common and can easily heal suddenly turn into a breathless infection? Is it something to do with my immune system? Or something that I'd been doing the days before I got sick?

Most upper respiratory infections are viral in nature, and laryngitis just means something has inflammed your larynx, or vocal chords. Sometimes they give you antibiotics to help prevent anything bacterial moving in while it has the chance- bacteria and viruses can be pretty nasty that way. Antibiotics don't have any effect on a virus, though. It could be you were just particularly sensitive to the one you caught, and it managed to get the upper hand fairly quickly before your body could respond and kick viral butt. It's not common for that to happen, no- not with an otherwise healthy adult. But it can and does happen. Could be you were a little extra run down when you caught your buggie, could be you were burning the candle at both ends when you first got sick. If you were trying to supress the fever that shows up sometimes, it could be that's what gave it the upper hand. Fever is not an enemy to you unless it gets over 102, or you aren't holding down fluids. Your body cells can work quite well in higher temperatures, but a virus or bacteria can't reproduce - it's a good first defense to limit the invading numbers. But if you supressed your fever with aspirin, Motrin or Tylenol, you could have provided just enough boost to the virus to let it get ahead. Honestly, though, it's usually a combination of these things, and sometimes it's just one tough bug. It's not always possible to say with certainty why a virus barely bothers one person and puts another one on their back in the hospital. Think back to things you were doing or not doing in those days just as you were getting sick, and those few days before it took the nasty turn. If you weren't exactly resting and drinking plenty, and were fighting the fever to get it back down to normal levels, then you may have been the deciding factor. If you were just tired and worn out when you got sick, it may be your immune system wasn't quite all that it should have been. And it may just have been one tough buggie. I wouldn't spend a lot of time worrying about it, though. Just keep in mind, when you get sick- don't fight to keep a fever at normal levels. Things aren't normal, and the higher temperature is actually an aid to your body fighting. Rest, sleep, drink loads and eat well. That will give you the best shot at beating whatever buggie you are up against. And sometimes, well- you just need a little something else to help.

For the infection to spread, is a common complication of any infection anywhere.
As long as you are using "suitable" antibiotics, and as you had been admitted then most probably you are. Do not worry.
If it is repeated infectionS, everywhere most of the time, then think of something wrong in your immune system. Otherwise,
take medications prescribed and relax.