Just to bring this topic alive, I've recently experienced all the symptoms described above. This is why I came looking here.
I've recently started noticing that when I am on meth and a couple of day after I get this shortness of breath sensation. It can be described as sometimes having to make every breath a deep one as if a short on is not enough, or other times a feeling like you need a deep breath but you just can't get it. No with this come chest pains when you beathe in. I've had a number of theories.
I would really appreciate if people revisited this thread and gave their opinions.
Theory 1.
The breathing is purely phsyco-sematic and is due to exiety. I have partially fixed and solved this problem by concentrating on taking specific normal little breaths when I feel like I am not getting enough oxygen. after about 5 breaths like that you realise that you are fine, you are not passing out. ie. you chill out and beat this anxiety attack. I've had anumber of other theories such as my lungs are fucked from meth and alviolae are not absorbing oxygen properly (sound like meth psycosis doesn't it?

. I am 99% its anxiety. Try it next time, just chill and keep taking normal breaths - you realise that you don't actually NEED to breathe deeper. This way also when you need to yawn to get a satisfying intake of oxygen, you can do it properly because you haven't wasted all your deep breaths on a poxy anxiety attack.
Theory 2.
The chest pains are partially due to beathing too deep and irregularly during anxiety attacks, or as a direct result of anxiety attack.
Theory 3.
It not always the left chest that hurts and it usually only hurts when you breathe in. This rules out a problem with the heart doesn't it?
Theory 4.
A lot of the times when I smoke meth I tend to sit on one spot and dribble shit. I often find that when I move, my whole body is kind of sore and fucked up. Could the chest pains be related to this too?
Theory 4.
Sometimes I get a funny tingling in hands - but not always in my left. It almost feels like fast throbbing. At times the whole body does this. But goes away after 5 - 10 minutes. Two weekends ago I got this, but after a subsequent cold shiver, the sensation disappeared, as if the shiver flushed it out of me. So another words whatever that sensation was, another more powerful sensation kind of snapped me out of it. Surelly, if the sensation was a sign of something gone really bad, it wouldn't go away just like that would it?
In conclusion, I've been taking meth (high quality - about 2 points) every weekend. Mostly because most of the above symptoms disappear by the next weekend. I haven't taken meth last weekend to ensure all symptoms are gone, but I might this coming weekend, so I'll report the experience.
P.s. Reading other peoples' posts and writing this made my breathing funny again and a slight discomfort in left chest. I think I can safelly put most of the things described above to panic/anxiety attacks or muscular pain resulting from the physical stress/discomfort you put on your body while on meth.