This used to happen to me all the time when I was young - like around 10? - exactly as you described it. I think at first I just thought it was normal, and that the world was just moving really fast, and then one day I thought to ask my dad about it, and he told me that nothing was going any faster then normal. I used to really hate it. It scared me a lot, and there was never really anything I could do to make it more bearable. I tried doing everything extra slowly, but that just brought attention to how fast everything was going. I tried doing everything extra fast to keep up with it; but you can't keep up with it and it just goes even faster and made my heart pump really fast and was even scarier. I tried sitting really still in a quiet place, but then my ears would start buzzing with the silence. After a while I just learnt to wait them out. I don't think I ever thought of the breathing thing. They slowly became more and more rare though. I'm 18 now and I hardly ever get them anymore. I think I had one for the first time in ages the other day, but it only lasted for 1-2 minutes instead of the 10-20 they used to last for. I knew what it was though, so it didn't freak me out as much as it used to. I think I may have had the optical allusion feeling a few times to, but not as bad as you're describing it (or maybe it was, I can't really remember?).
I've never thought to look this up until now (not thinking that anyone else had experienced it). The reason I'm looking it up now is because I was reading a story where the main character has diagnosed bipolar disorder, and the author described him experiencing this sped up, fast forward type of thing during his manic episodes. I experienced on/off (mainly on) depression (undiagnosed because I couldn't bring myself to talk about it or admit to it until the last year or two) for about six years. It wouldn't really be a stretch to think I'd been experiencing manic depression (bipolar disorder) instead of clinical depression. (I'm pretty sure I'm better now though - haven't had an episode in at least six months).

It's kind of reassuring to know that there are other people who have experienced this fast forward thing too. I hope things get better for you. If you manage to figure out why it happens, do you think you could reply and let me know?