BF vs solids?

OK, so lately Caitlyn is pretty much refusing to nurse during the day, and I'm not sure what to do about it. She will latch for all of 30 seconds, and then turns away. But if I offer her solids, she will gobble it all up. I even tried a bottle to see if it was a flow issue- nope, she just wants the solids. She's 8mos, but isn't she still supposed to be getting the bulk of her nutrition from breastmilk? I can feel my supply has majorly dropped because of this, and that brings on another question.

Everytime I try to nurse more frequently, I get an itchy red rash around my nipples. It isn't there all the time, only when I increase frequency. What's that all about?? I put lotrimin on, in case it's yeast, but that doesn't seem to help. The only thing that has seemed to calm it is benadryl cream, and vitamin E oil (which I of course wash off before nursing!). It goes away in a couple days, but it's really a PITA, and just don't know what's going on with that. The strange thing is, that I don't have it all the time, so that's why I'm not sure. If it were an around-the-clock thing, I'd think it's probably thrush, but it really is only when I try to nurse more often, and it makes me not want to try!