back on chemo, scared & questions

I have bone mets;er+,her2+. I was on taxotere/herceptin for 6 momths, it reduced the tumor, but didn't put it into remission. Then I was on faslodex 6 months & now there's more tumor activity on PET scan. So, now I'm starting navelbine/herceptin. After 1 treatment, I had no nausea, but lots of kind of cramping in my stomach, and also lots of joint/muscle pains. Some questions I have........ Do people take l-glutamine for stomach discomfort? does it interfere with chemo? harmful? helpful? Could navelbine be effective even if taxotere wasn't? On PET scan it showed "more tumor activity" from a 9 to 15 in one spot, from 3 t0 9 in another, etc. Is this signficant? How do you interpret the numbers? My ca2729 was 55, up from 41 the month before. I'm so distressed right now, feeling like my window for hope has shrunken smaller. Any one have similar experience or helpful information. I find a lot of wisdom in reading this board. Thank you.