Sorry you find yourself here, but welcome, there's lots of info and support.
Being new and confused is par for the course--very normal I think.
I suspect this soon after diagnosis it could be difficult to know with certainty if you're RRMS or progressive. Relapses can last a long time before they remit so I wouldn't automatically assume you're progressive just because it sounds like you haven't had much relief yet.
Re: the changing symptoms with your legs and walking, I think that's also par for the course. In my experience, symptoms come and go on an hourly, daily, weekly basis--with time you'll probably become pretty adept at knowing what to avoid and what helps.
I'm on Copaxone and haven't had the chest pressure last all day--I don't think I've had it all actually. I think you probably want to let your neuro know about that.
Hopefully some others will chime in too with their thoughts. Being newly diagnosed can be overwhelming--
Take care--wishing you the best