Miranda
I am a swimmer
I am asthmatic
I can relate

I started swimming again about 7 years ago after a VERY long hiatus. Luckily I started swimming under an amazing coach (she just got back in Jan from Guam where she was a coach for the USA jr Pan Pacific team) Just had to put that plug in She is a coworker of mine at the school I teach at.

ANYWAY if you really want to learn how to swim and to do it correctly take some lessons from a reputable coach, watch Total Immersion videos, AND buy a good swimming snorkel for about $30. Swim w/ the snorkel until you have the body roll, arms and kick memorized, that totally takes care of the asthmatic panic that can set in. Wearing swim fins helps a lot too.

Now after 2 years off I started back in Sept and wore the snorkel and zoomer fins again for 3.5 months and I was swimming 3-4 days per week - I just dropped them in Dec. Today for my last 500 I put the snorkel on again because I was wheezing.

Re shoulder pain. I am guessing this isn't a repetition injury. Again - learn the drills and concentrate on them before trying to do the full stroke. Once you get the body roll down, your arms will come out of the water better, and eventually the breathing will come naturally. My guess is right now you are working way harder than you need to because you aren't efficient yet.

Wear the snorkel, do lots drill laps, get efficient, then learn the breathing - it works.