I think you will see some improvements soon. DS2 started to tolerate a better variety of foods around 8mos and we started incorporating dairy back in around then. Not saying you should (his intolerances seemed really mild), but you may find that his gut does mature a bit more over the next coming weeks which will hopefully open more doors for you.
The probiotics should really help but you will have to look for ones that are dairy free as a lot of them contain it.
Maybe this is something your doctor could help you with, but if you can talk to one a naturopath would really be able to help recommend an appropriate one.
Definitely try the open cup. Even if it spills a lot at first, they learn pretty quickly. It would really help if you can get some more fluids into him.